1

Antineutrino Detectors Remain Impractical for Nuclear Explosion Monitoring Michael Foxe1, Theodore Bowyer1, Rachel Carr2, John Orrell1, Brent VanDevender1

1) Pacific Northwest National Laboratory, Richland, WA, USA 99352 2) Massachusetts Institute of Technology, Cambridge, MA, USA 02139

Michael.Foxe@pnnl.gov

Abstract: Fission explosions produce large numbers of antineutrinos. It is occasionally asked whether this distinctive, unshieldable emission could help reveal clandestine nuclear weapon explosions. The practical challenge encountered is that detectors large enough for this application are cost prohibitive, likely on the multi-billion-dollar scale. In this paper, we review several hypothetical use cases for antineutrino detectors as supplements to the seismic, infrasound, hydroacoustic, and airborne radionuclide sensors of the Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System. In each case, if an anti-neutrino detector could be constructed that would compete with existing capabilities, we conclude that the cost would considerably outstrip the value it might add to the existing monitoring network, compared to the significantly lower costs for the same or superior capability. Keywords: antineutrino, nuclear explosion monitoring, radioxenon, CTBTO PrepCom

Proceedings of the 2018 CERN–Accelerator–School course on Beam Instrumentation, Tuusula, (Finland)

Available online at https://cas.web.cern.ch/previous-schools 1

Measuring Tune, Chromaticity and Coupling

Rhodri Jones CERN, Geneva, Switzerland

Abstract This chapter takes a look at the ways tune, chromaticity and coupling can be measured in synchrotrons. After briefly introducing the importance of these parameters for machine operation, a broad overview of the various instrumentation and analysis techniques used in their determination will be given.

Keywords Beam Instrumentation; Tune; Chromaticity; Coupling

1 Introduction The instrumentation used to observe transverse beam motion is very important for the efficient operation of any circular accelerator. There are three main parameters that can be determined using such diagnostics, namely the betatron tune, chromaticity and betatron coupling, all of which are discussed in detail in this chapter.

2 Betatron Tune The betatron tune is a characteristic of the magnetic lattice and is defined, to first order, by the strength of quadrupole magnets. It can be thought of as the number of oscillations a particle which is not on the central orbit (defined by the centre of all quadrupoles) will undergo while completing a full revolution. The full betatron tune, Q, can be split into two components: the integer tune, defined as the number of complete oscillations the particle undergoes during one revolution, and the fractional tune, q, representing the fractional difference in the phase of the oscillation from one turn to the next. It is typically this fractional part of the tune that is measured to find the optimal working point for the accelerator.

Fig. 1: The betatron tune is the characteristic frequency of the magnetic lattice and can be represented by an integer part and a fractional part

The integer tune is typically measured by looking at the residual betatron pattern imprinted on the global beam orbit using the accelerator’s beam position measurement system, while the fractional part

This is a pre-print of an article accepted for publication in the Journal of Geodesy.

Methods for coherent optical Doppler orbitography

Benjamin P. Dix-Matthews1,2 · Sascha W. Schediwy1,2 · David R. Gozzard3 · Simon

Driver1 · Karl Ulrich Schreiber4 · Randall Carman5 · Michael Tobar2

Abstract Doppler orbitography uses the Doppler shift

in a transmitted signal to determine the orbital parame-

ters of satellites including range and range-rate (or radial

velocity). We describe two techniques for atmospheric-

limited optical Doppler orbitography measurements of

range-rate. The first determines the Doppler shift di-rectly from a heterodyne measurement of the returned

optical signal. The second aims to improve the preci-

sion of the first by suppressing atmospheric phase noise

imprinted on the transmitted optical signal. We demon-

strate the performance of each technique over a 2.2 km

horizontal link with a simulated in-line velocity Doppler

shift at the far end. A horizontal link of this length has

been estimated to exhibit nearly half the total integrated

atmospheric turbulence of a vertical link to space. With-

out stabilisation of the atmospheric effects, we obtained

an estimated range rate precision of 17 µm s−1 at 1 s

This research was supported by the Australian ResearchCouncil’s Linkage Infrastructure, Equipment and Facilities(LE160100045) funding scheme; the Australian Research Coun-cil’s Centre of Excellence for Engineered Quantum Systems(EQUS, CE170100009); and the International Centre for RadioAstronomy Research.

� Benjamin P. Dix-Matthewsbenjamin.dix-matthews@research.uwa.edu.au

1 International Centre for Radio Astronomy Research, TheUniversity of Western Australia, Perth, Australia

2 Australian Research Council Centre of Excellence for En-gineered Quantum Systems, The University of WesternAustralia, Perth, Australia

3 Department of Quantum Science, Research School ofPhysics, The Australian National University, Canberra,Australia.

4 Research Unit Satellite Geodesy, Technical University ofMunich, Munich Germany

5 Geoscience Australia, Dongara, Australia

of integration. With active suppression of atmospheric

phase noise, this improved by three orders-of-magnitude

to an estimated range rate precision of 9.0 nm s−1 at 1 s

of integration, and 1.1 nm s−1 when integrated over a

60 s. This represents four orders-of-magnitude improve-

ment over the typical performance of operational groundto space X-Band systems in terms of range-rate precision

at the same integration time.

The performance of this system is a promising proof

of concept for coherent optical Doppler orbitography.

There are many additional challenges associated with

performing these techniques from ground to space, that

were not captured within the preliminary experiments

presented here. In the future, we aim to progress to-wards a 10 km horizontal link to replicate the expected

atmospheric turbulence for a ground to space link.

Keywords Doppler orbitography · Free-space coherent

optical link · Satellites · Phase stabilisation · Frequency

transfer · Atmospheric turbulence · Optical transmission

1 Introduction

Doppler orbitography uses the Doppler shift on a one-

way (Auriol and Tourain, 2010) or two-way (Iess et al,

2014) transmission to determine orbital parameters of

satellites. The Doppler Orbitography and Radio posi-

tioning Integrated by Satellite (DORIS) system oper-

ates at two frequencies (2036.25 MHz and 401.25 MHz)

and is used around the world for geodesy (Auriol and

Tourain, 2010). This one-way system determines the

range rate (or radial velocity) of the satellite at uncer-

tainties of <0.4 mm s−1 (Moreaux et al, 2019). Typical

operational ground to space X-band radio tracking tech-

niques can now achieve precisions at around 20 µm s−1 to

100 µm s−1 after 60 s of integration (Dirkx et al, 2018).

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Measurement of the temperature distribution

inside a calorimeter

Ákos SudárEngineering Developer, Faculty of Mechanical Engineering,

Budapest University of Technology and Economics,

Supervisor:

Dr. Róbert Kovács, Ph.D.

Assistant professor, Department of Energy Engineering,

Budapest University of Technology and Economics,

Department of Theoretical Physics, Institute for Particle and Nuclear Physics, Wigner

Research Centre for Physics

Consultants:

Researcher, Mónika Varga-Kőfaragó, Ph.D.

RMI High Energy Experimental Particle and Heavy Ion Physics,

Wigner Research Centre for Physics

Dieter Røhrich, Ph.D.

Professor, Department of Physics and Technology,

University of Bergen

Budapest, 2019

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Abstract

Hadron therapy is a novel treatment against cancer. The main advantage of this therapy

causes less side effect in comparison to X-ray irradiation methods. Hadron therapy is just

ahead of a significant breakthrough since this technique can be more precise, applying proton

computer tomograph (pCT) to map the stopping power in the tissues.

The research and development of a pCT require a fast detector to measure the energy of

hadrons behind the patient. The best detector option is called hadron-tracking calorimeter,

which consists of sandwich layers of silicon tracking detectors and absorber layers. The combi-

nation of measuring the trajectory (tracking process), and, in parallel, the energy of relativistic

particles, can provide high-resolution hadron imaging. This semiconductor-based technology

requires stable temperature and homogeneous cooling.

I have worked in the development of this detector in the Bergen pCT Collaboration for two

years. Last year my work was to investigate the temperature distribution in the calorimeter and

examine two cooling concepts in detail. I performed both analytical and numerical calculations

to analyze the temperature distribution of the calorimeter. The final decision about the design

takes into account many engineering aspects, such as reliability, flexibility, and performance.

Eur. Phys. J. C manuscript No.(will be inserted by the editor)

Cryogenic characterization of a LiAlO2 crystal and new results onspin-dependent dark matter interactions with ordinary matter

A. H. Abdelhameed1, G. Angloher1, P. Bauer1, A. Bento1,9, E. Bertoldo?,a,1, R. Breier2,C. Bucci3, L. Canonica1, A. D’Addabbo3,10, S. Di Lorenzo3,10, A. Erb4,11, F. v. Feilitzsch4,N. Ferreiro Iachellini1, S. Fichtinger5, D. Fuchs1, A. Fuss5,6, V.M. Ghete5,6, A. Garai1,P. Gorla3, D. Hauff1, M. Ješkovský2, J. Jochum7, J. Kaizer2, M. Kaznacheeva4,A. Kinast4, H. Kluck5,6, H. Kraus8, A. Langenkämper4, M. Mancuso?,b,1, V. Mokina5,E. Mondragon4, M. Olmi3,10, T. Ortmann4, C. Pagliarone3,12, V. Palušová2,L. Pattavina3,4, F. Petricca1, W. Potzel4, P. Povinec2, F. Pröbst1, F. Reindl5,6, J. Rothe1,K. Schäffner1, J. Schieck5,6, V. Schipperges7, D. Schmiedmayer5,6, S. Schönert4,C. Schwertner5,6, M. Stahlberg1, L. Stodolsky1, C. Strandhagen7, R. Strauss4,I. Usherov7, F. Wagner5,6, M. Willers4, V. Zema3,10,13, J. Zeman2 (The CRESSTCollaboration)andM. Brützam14, S. Ganschow14

1Max-Planck-Institut für Physik, D-80805 München, Germany2Comenius University, Faculty of Mathematics, Physics and Informatics, SK-84248 Bratislava, Slovakia3INFN, Laboratori Nazionali del Gran Sasso, I-67100 Assergi, Italy4Physik-Department and Excellence Cluster Universe, Technische Universität München, D-85748 Garching, Germany5Institut für Hochenergiephysik der Österreichischen Akademie der Wissenschaften, A-1050 Wien, Austria6Atominstitut, Vienna University of Technology, A-1020 Wien, Austria7Eberhard-Karls-Universität Tübingen, D-72076 Tübingen, Germany8Department of Physics, University of Oxford, Oxford OX1 3RH, United Kingdom9also at: Departamento de Fisica, Universidade de Coimbra, P3004 516 Coimbra, Portugal10also at: GSSI-Gran Sasso Science Institute, 67100, L’Aquila, Italy11also at: Walther-Meißner-Institut für Tieftemperaturforschung, D-85748 Garching, Germany12also at: Dipartimento di Ingegneria Civile e Meccanica, Università degli Studi di Cassino e del Lazio Meridionale, I-03043 Cassino, Italy13also at: Chalmers University of Technology, Department of Physics, SE-412 96 Göteborg, Sweden14Leibniz-Institut für Kristallzüchtung, D-12489 Berlin, GermanyReceived: date / Accepted: date

Abstract In this work, a first cryogenic characterization ofa scintillating LiAlO2 single crystal is presented. The re-sults achieved show that this material holds great potentialas a target for direct dark matter search experiments. Threedifferent detector modules obtained from one crystal grownat the Leibniz-Institut für Kristallzüchtung (IKZ) have beentested to study different properties at cryogenic tempera-tures. Firstly, two 2.8 g twin crystals were used to build dif-ferent detector modules which were operated in an above-ground laboratory at the Max Planck Institute for Physics(MPP) in Munich, Germany. The first detector module wasused to study the scintillation properties of LiAlO2 at cryo-genic temperatures. The second achieved an energy thre-shold of (213.02±1.48) eV which allows setting a competi-tive limit on the spin-dependent dark matter particle-proton

?Corresponding authorsabertoldo@mpp.mpg.debmancuso@mpp.mpg.de

scattering cross section for dark matter particle masses be-tween 350 MeV/c2 and 1.50 GeV/c2. Secondly, a detectormodule with a 373 g LiAlO2 crystal as the main absorberwas tested in an underground facility at the Laboratori Nazio-nali del Gran Sasso (LNGS): from this measurement it waspossible to determine the radiopurity of the crystal and studythe feasibility of using this material as a neutron flux moni-tor for low-background experiments.

Keywords Dark matter · Cryogenics · Spin-Dependent ·Lithium · Neutrons

Compiled on May 7, 2020

1 Introduction

In the past few decades, great effort has been devoted tothe investigation of dark matter [1]. One path which could

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Prototype of a segmented scintillator detector for particleflux measurements on spacecraft

Egor Stadnichuk1,2 Tatyana Abramova1 Mikhail Zelenyi1,2,3 Alexander Izvestnyy2 AlexanderNozik1,2 Vladimir Palmin1,2 Ivan Zimovets3

1Moscow Institute of Physics and Technology (National Research University) - MIPT, 1 "A" Kerchenskayast., Moscow, Russia, 117303

2Institute for Nuclear Research of the Russian Academy of Sciences (INRRAS), Prospekt 60-letiya Oktyabrya7a, Moscow, Russia, 117312

3Space Research Institute of the Russian Academy of Sciences (IKI RAS), 84/32 Profsoyuznaya st., Moscow,Russia, 117997

E-mail: yegor.stadnichuk@phystech.edu

Abstract: In this paper we introduce a laboratory prototype of a solar energetic particle (SEP)detector which will operate along with other space-based instruments to give us more insight intothe SEP physics. The instrument is designed to detect protons and electrons with kinetic energiesfrom 10 to 100 MeV and from 1 to 10 MeV respectively. The detector is based on a scintillationcylinder divided into separated disks to get more information about detected particles. Scintillationlight from isolated segments is collected by optical fibers and detected with silicon photo-multipliers(SiPM). The work contains the result of laboratory testing of the detector prototype. The detectorchannels were calibrated, energy resolution for every channel was obtained. Moreover, we presentan advanced integral data acquisition and analysis technique based on Bayesian statistics, whichwill allow operation even during SEP events with very large fluxes.

The work is motivated by the need for better measurement tools to study acceleration andtransport of SEP in the heliosphere as well as by the need for monitoring tool to mitigate radiationhazard for equipment and people in space.

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Plastic Scintillation Detectors for Time-of-Flight Mass Measurements

K. Wanga,b,c,∗, A. Estradea,c,d,∗, S. Neupanea,1, M. Barbera, M. Famianoe,c, T. Ginterd, D. McClaina,2, N. Nepala,c, J.Pereirad, H. Schatzd,c, G. Zimbaa,3

aDepartment of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, USAbInstitute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gausu 730000, China

cJoint Institute for Nuclear Astrophysics Center for the Evolution of the Elements (JINA-CEE), USAdNational Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA

eDepartment of Physics, Western Michigan University, Kalamazoo, Michigan 49008, USA

Abstract

Fast timing detectors are an essential element in the experimental setup for time-of-flight (ToF) mass measurementsof unstable nuclei. We have upgraded the scintillator detectors used in experiments at the National SuperconductingCyclotron Laboratory (NSCL) by increasing the number of photomultiplier tubes that read out their light signals to fourper detector, and characterized them in a test experiment with 48Ca beam at the NSCL. The new detectors achieved atime resolution (σ) of 7.5 ps. We systematically investigated different factors that affect their timing performance. Inaddition, we evaluated the ability of positioning the hitting points on the scintillator using the timing information andobtained a resolution (σ) below 1 mm for well-defined beam spots.

Keywords: Time-of-flight mass measurement; Plastic scintillator; Photomultiplier tubes; Time-walk correction

1. Introduction

Nuclear masses, and nuclear binding energies, play acentral role in many questions of nuclear structure andnuclear astrophysics [1, 2]. Nuclear masses provide oneof the main tools to understand the evolution of nuclearstructure away from β-stability through systematic trendsin binding energies [3, 4], and are an essential input fornuclear astrophysics models [5, 6].

At present there is a variety of techniques and devicescapable of measuring the mass of isotopes at different re-gions across the nuclear chart, and with various degreesof precision: Penning trap spectrometers [7, 8, 9, 10, 11,12, 13], storage rings [14, 15, 16, 17], multi-reflection time-of-flight (MR-ToF) spectrometers [18, 19, 20, 21, 22], andtime-of-flight measurements with magnetic spectrometers(ToF-Bρ technique) [23, 24]. The latter has a relativelylow mass resolving power with m/∆m ∼ 104, but canmeasure with high efficiency the masses of many unstableisotopes far from β-stability. The technique is currentlyused with the S800 spectrometer at the National Super-conducting Cyclotron Laboratory (NSCL) [23, 25], which

∗Corresponding authorsEmail addresses: wang5k@cmich.edu (K. Wang),

estra1a@cmich.edu (A. Estrade)1Present address: Department of Physics and Astronomy, Uni-

versity of Tennessee, Knoxville, Tennessee 37996, USA2Present address: Department of Physics and Astronomy, Texas

A&M University, College Station, Texas 77843, USA3Present address: Department of Physics, University of

Jyvaskyla, P.O. Box 35, FI-40014, Jyvaskyla, Finland

is the focus of this work, and with the SHARAQ spectrom-eter at RIKEN [26].

The principle of the ToF-Bρ technique is based on themotion law of an ion with mass m, charge q and momen-tum p passing through a beam line and magnetic spec-trometer with a total flight path of length L. If its time-of-flight is given by T , the nuclear mass is related to thesevariables by:

m = p ·

√

(

T

L

)2

−1

c2= qBρ ·

√

(

T

L

)2

−1

c2, (1)

where c is the speed of light, and Bρ = p/q is the mag-netic rigidity of this ion with radius of curvature ρ for theparticle trajectory.

In order to obtain masses, T must be measured withvery high precision using timing detectors at the start andend points of the flight path. The momentum p can be ob-tained from measuring the ion’s position x in a dispersiveplane of the spectrometer. To first order:

p = p0

(

1 +x

D

)

, (2)

where p0 = q(Bρ)0 is the momentum of the central trajec-tory, and D is the dispersion function. The electric chargeq of the beam ions is evaluated with a relation based on thetotal kinetic energy, velocity and magnetic rigidity com-bining with the ∆E-ToF particle-identification technique[27].

However, L and Bρ usually cannot be measured withsufficient accuracy. Therefore, in practice, we can derive

Preprint submitted to Nuclear Instruments and Methods in Physics Research Section A May 7, 2020

Neutron production in (α, n) reactions

V. A. Kudryavtsev∗, P. Zakhary, B. Easeman

Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, United Kingdom

Abstract

Neutrons can induce background events in underground experiments looking for rare pro-cesses. Neutrons in a MeV range are produced in radioactive decays via spontaneous fissionand (α, n) reactions, and by cosmic rays. Neutron fluxes from radioactivity dominate at largedepths (> 1 km w. e.). A number of computer codes are available to calculate cross-sectionsof (α, n) reactions, excitation functions and neutron yields. We have used EMPIRE2.19/3.2.3and TALYS1.9 to calculate neutron production cross-sections and branching ratios for transi-tions to the ground and excited states, and modified SOURCES4A to evaluate neutron yieldsand spectra in different materials relevant to high-sensitivity underground experiments. Wereport here a comparison of different models and codes with experimental data, to estimatethe accuracy of these calculations.

Keywords: Radioactivity, Neutron production, (α, n) reactions, Undergroundexperiments, Neutron background

1. Introduction

Underground experiments looking for rare events, such as dark matter WIMPs, neutrino-less double-beta decay or low-energy neutrinos, are combatting various backgrounds, someof which are caused by neutrons. Neutrons may produce single-hit events in dark matterexperiments indistinguishable from WIMP interactions. Neutron inelastic scattering andhigh-energy gammas from neutron capture give a background in a region of interest for neu-trinoless double-beta decay search. Neutron interactions can also mimic signatures expectedfrom low-energy neutrinos.

Since these experiments are usually located at large depths underground (> 1 km w. e.),we will consider here the mechanisms for neutron production relevant to underground ex-periments. Neutrons from atmospheric showers do not penetrate hundreds metres of rockwhereas neutron fluxes from cosmic-ray muons are suppressed by several orders of magnituderelative to shallow depths. Also, muon-induced events can be tagged in experiments by acoincident detection of a muon or other particles in a muon-initiated cascade. This makesradioactive decays the main source of neutron background at large depths. Two processescontribute to neutron production of this origin: spontaneous fission and (α, n) reactions.

Spontaneous fission (SF), as described by Watt’s formulae [1], gives the same neutronyield for all materials and depends only on the concentration of the fissioning isotope. Among

∗corresponding author: V. A. Kudryavtsev, v.kudryavtsev@sheffield.ac.uk

Preprint submitted to Elsevier May 7, 2020

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Small Bragg-plane slope errors revealed in synthetic diamond crystals

Paresh Pradhan,1 Michael Wojcik,1 Xianrong Huang,1 Elina Kasman,1 Lahsen Assoufid,1 Jayson

Anton,1 Deming Shu,1 Sergey Terentyev,2 Vladimir Blank,2 Kwang-Je Kim,1 and Yuri Shvyd’ko1, ∗

1Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA2Technological Institute for Superhard and Novel Carbon Materials, 142190 Troitsk, Russian Federation

Wavefront-preserving x-ray diamond crystal optics are essential for numerous applications in x-rayscience. Perfect crystals with flat Bragg planes are a prerequisite for wavefront preservation in Braggdiffraction. However, this condition is difficult to realize in practice because of inevitable crystalimperfections. Here we use x-ray rocking curve imaging to study the smallest achievable Bragg-planeslope errors in the best presently available synthetic diamond crystals and how they compare withthose of perfect silicon crystals. We show that the smallest specific slope errors in the best diamondcrystals (both freestanding or strain-free mounted) are about 0.15-0.2 µrad/mm2. These errors areonly a factor of two larger than the 0.05-0.1 µrad/mm2 specific slope errors we measure in perfectsilicon crystals. High-temperature annealing at 1450◦C of almost flawless diamond crystals reducesthe slope errors very close to those of silicon. Further investigations are required to establish thewavefront-preservation properties of these crystals.

PACS numbers:

I. INTRODUCTION

Diamond features a unique combination of outstand-ing physical properties perfect for numerous x-ray crys-tal optics applications where traditional materials suchas silicon fail to perform. Diamond is a material ofchoice in applications requiring improved transparencyto x-rays, highest x-ray Bragg reflectivity, thermal con-ductivity, mechanical stiffness, and resilience to radiationdamage. Diamond optics are essential for tailoring x-raysto the most challenging needs of x-ray research. Diamondoptics are becoming vital for generation of fully coherenthard x-rays by seeded x-ray free-electron lasers [see re-cent review paper [1] for details and references].

Progress in fabrication of synthetic high-quality di-amond crystals has been substantial in the last twodecades. Crystals with defect-free areas of ' 4× 4 mm2

and more grown by a temperature gradient method un-der high pressure and high temperature (HPHT) are nowstate of the art [2–6]. However, the perfection of diamondcrystals is typically not as high as of silicon crystals,which are standard in x-ray crystal optics applications.In particular, the wavefront-preservation properties, crit-ical for many applications, suffer from insufficient crystalquality.

Perfect crystals with flat Bragg planes are a prerequi-site for wavefront preservation in Bragg diffraction. Butnothing is perfect. How flat can Bragg crystal planes bein the best available diamond crystals? What are thesmallest achievable Bragg-plane slope errors in the bestpresently available synthetic diamond crystals? How dothese compare to those in perfect silicon crystals? Thesequestions are addressed in the present paper.

In the studies presented in this paper, Bragg-plane

∗Electronic address: shvydko@anl.gov

slope errors are measured using x-ray Bragg diffractionrocking curve imaging (RCI), also known as sequentialtopography [7]. This technique is applied to best avail-able diamond crystals featuring relatively large areas(' 4×4 mm2) almost free of dislocations, stacking faults,inclusions, and other defects detectable by white beamx-ray topography [8, 9], which is used to prescreen thediamond crystals. The Bragg-plane slope errors in dia-mond crystals are compared to those in highest qualityreference silicon crystals.

We show that the smallest specific slope errorsin the best diamond crystals are about σ∗

θ' 0.15-

0.2 µrad/mm2, which are only a factor of two larger thanthe . 0.1 µrad/mm2 slope errors we measure in referencesilicon crystals. Such small slope errors are achieved notonly in freestanding diamond crystals but also in crystalsfirmly mounted in crystal holders, provided the crystalsare designed and machined with special strain-relief fea-tures. High-temperature annealing at 1450◦C of the bestdiamond crystals further reduces Bragg-plane slope er-rors, such that hey approach those of silicon.

RCI data also provides access to the specific disper-sion σ

∆θof the rocking curve widths ∆θ. Normalized to

the Bragg reflection width ∆θ, it is a measure of the de-viation from the largest Bragg reflectivity achievable byperfect crystals. The best diamond crystals feature nor-malized specific dispersion values Σ∗

∆θ' 0.01-0.013/mm2

vs. ' 0.003-0.005/mm2 in silicon. These data indicatesthat the local reflectivity values in the best diamond crys-tals are reduced by not more than 1% to 1.3% from themaximum values, in agreement with previous Bragg re-flectivity studies in diamond [4].

Further investigations are required to establish thewavefront-preservation properties of the best available di-amond crystals.

The paper is organized as follows. In Section II weprovide results of the RCI studies in a reference siliconcrystal. Results of studies in selected freestanding dia-

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Transmission of xenon scintillation light through PTFE

D. Cichon,a,1 G. Eurin, a,2 F. Jörg,a,1 T. Marrodán Undagoitia,a N. Ruppa

aMax-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

E-mail: dominick.cichon@mpi-hd.mpg.de, florian.joerg@mpi-hd.mpg.de

Abstract: Polytetrafluoroethylene (PTFE), also known as Teflon, is a common material used inthe construction of liquid xenon detectors due to its high reflectivity for the VUV scintillationlight of xenon. We present transmission measurements of PTFE for xenon scintillation light withpeak emission at a wavelength of 175 nm. PTFE discs of different thicknesses are installed infront of a photosensor in two setups. One is filled with gaseous xenon, the other with liquidxenon. The measurements performed with the gaseous xenon setup at room temperature yield atransmission coefficient of λ =

(350+60

−0 (sys) ± 50 (stat))µm. This is found to be in agreement with

the observations made using the liquid xenon setup.

Keywords: Noble liquid detectors, detector design and construction technologies and materials,dark matter detectors, double beta decay detectors

1corresponding author2now at CEA/Saclay, IRFU (Institut de Recherche sur les Lois Fondamentales de l’Univers), F-91191 Gif-sur-Yvette

CEDEX, France

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Freeze-in Dirac neutrinogenesis: thermal

leptonic CP asymmetry

Shao-Ping Li,a Xin-Qiang Li,a,1 Xin-Shuai Yana and Ya-Dong Yanga

aInstitute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE),

Central China Normal University,Wuhan, Hubei 430079, China

E-mail: ShowpingLee@mails.ccnu.edu.cn, xqli@mail.ccnu.edu.cn,

xinshuai@mail.ccnu.edu.cn, yangyd@mail.ccnu.edu.cn

Abstract: We present a freeze-in realization of the Dirac neutrinogenesis in which

the decaying particle that generates the lepton-number asymmetry is in thermal equi-

librium. As the right-handed Dirac neutrinos are produced non-thermally, the lepton-

number asymmetry is accumulated and partially converted to the baryon-number

asymmetry via rapid sphaleron transitions. The necessary CP-violating condition

can be fulfilled by a purely thermal kinetic phase from wavefunction correction in

the lepton-doublet sector, which has been neglected in most leptogenesis-based setup.

Furthermore, this condition necessitates a preferred basis in which both the charged-

lepton and neutrino Yukawa matrices are non-diagonal. Based on the tri-bimaximal

mixing with a minimal correction from the charged-lepton or neutrino sector, we find

that a simultaneous explanation of the baryon-number asymmetry in the Universe

and the low-energy neutrino oscillation observables can be attributed to the mixing

angle and the CP-violating phase introduced in the minimal correction.

1Corresponding author.

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Quantum black holes in the horizon quantummechanics model at the Large Hadron Collider

Douglas M. Gingricha,b and Brennan Undseth∗,a

aDepartment of Physics, University of Alberta, Edmonton, AB T6G 2G7 CanadabTRIUMF, Vancouver, BC V6T 2A3 Canada

gingrich@ualberta.ca, brennan.undseth@gmail.ca

Abstract

Quantum black hole production at the Large Hadron Collider is investigated using thehorizon quantum mechanics model. This model has novel implications for how black holesmight be observed in collider experiments. Black hole production is predicted to be possiblebelow the Planck scale, thus leading to the intriguing possibility that black holes could beproduced even if the Planck scale is slightly above the collider centre of mass energy. Inaddition, the usual anticipated resonance in the black hole mass distribution is significantlywidened in this model. For values of the Planck scale above the current lower limits, theshape of the black hole mass distribution is almost independent of the Planck scale anddepends more on the number of extra dimensions. These model features suggest the needfor alternative search strategies in collider experiments.

1 Introduction

Low-scale gravity provides an interesting possibility for gaining insight into the hierarchy prob-lem. A wide variety of models based on different paradigms [1, 2, 3] have been proposed. Aspeculative, but intriguing, possibility of most models is the production of quantum black holesin hadron colliders [4, 5].

The cross section for black hole production is typically chosen to be the classical geometricform σ ≈ πr2g, where rg is the gravitational radius which is a function of the black hole massM and depends on the fundamental parameters of the model. In the large extra dimensionsparadigm proposed in Ref. [1, 2], the model parameters are the higher-dimensional Planck scaleMD and total number of space-time dimensions D. We will consider the case of a tensionlessnon-rotating spherically symmetric solution for the gravitational radius [6].

In proton–proton collisions, only a fraction of the total centre of mass energy√s is available

in the hard-scatter process. We define sxaxb ≡ sτ ≡ s, where xa and xb are the fractionalenergies of the two colliding partons (assumed massless) relative to the proton energies. Thefull particle-level cross section σ is obtained from the parton-level cross section σ by using [7]

σpp→BH+X(s) =∑a,b

∫ 1

M2/sdτ

∫ 1

τ

dx

xfa

(τx

)fb(x)Θ(M −Mth)σab→BH(s = M2) , (1)

∗Currently at Delft University of Technology, Netherlands.

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Polarized jet fragmentation functions

Zhong-Bo Kanga,b,c, Kyle Leed,e, Fanyi Zhaoa,b

aDepartment of Physics and Astronomy, University of California, Los Angeles, California 90095, USAbMani L. Bhaumik Institute for Theoretical Physics, University of California, Los Angeles, California 90095, USA

cCenter for Frontiers in Nuclear Science, Stony Brook University, Stony Brook, New York 11794, USAdC.N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, New York 11794, USA

eDepartment of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA

Abstract

We develop the theoretical framework needed to study the distribution of hadrons with general polarization inside jets,with and without transverse momentum measured with respect to the standard jet axis. The key development in thispaper, referred to as “polarized jet fragmentation functions”, opens up new opportunities to study both collinear andtransverse momentum dependent (TMD) fragmentation functions. As two examples of the developed framework, westudy longitudinally polarized collinear Λ and transversely polarized TMD Λ production inside jets in both pp and epcollisions. We find that both observables have high potential in constraining spin-dependent fragmentation functionswith sizeable asymmetries predicted, in particular, at the future Electron-Ion Collider.

Keywords: jets fragmentation functions, perturbative QCD, Soft Collinear Effective Theory, spin physics

1. Introduction

Over the last few years, the study of hadron distributions inside jets has received increasing attention as an effectivetool to understand the fragmentation process, describing how the color carrying partons transform into color-neutralparticles such as hadrons. Understanding such a fragmentation process is important as it will provide us with a deepinsight into the elusive mechanism of hadronization. Theoretical objects which describe the momentum distributionof hadrons inside a fully reconstructed jet is called jet fragmentation functions (JFFs). The usefulness of studyingthe longitudinal momentum distribution of the hadron in the jet rather than the hadron production itself stems fromthe former process being differential in the momentum fraction zh ≡ phT /pJT , where phT and pJT are the transversemomenta of the hadron and the jet with respect to the beam axis, respectively. Collinear JFFs in the first processcan be matched onto the standard collinear fragmentation functions (FFs), enabling us to extract the usual universalFFs more directly by “scanning” the differential zh dependence. The theoretical developments on the JFFs were firststudied in the context of exclusive jet production [1, 2, 3, 4] and was later extended to the inclusive jet productioncase [5, 6, 7, 8, 9].

At the same time, the transverse momentum distribution of the hadrons within jets can be sensitive to the trans-verse momentum dependent fragmentation, described by transverse momentum dependent jet fragmentation functions(TMDJFFs). In [10], it was demonstrated that such TMDJFFs are closely connected to the standard transverse mo-mentum dependent FFs (TMDFFs) [11, 12, 13] when the transverse momentum of the hadron is measured with respectto the standard jet axis. For the TMD study of the hadron with respect to the Winner-Take-All jet axis, see [14, 15].As for the TMD study inside the groomed jet, see [16, 17, 18]. For the recent works on resummation of ln zh andln(1 − zh), see [19, 20].

Because of its phenomenological relevance and effectiveness, study of the JFFs has become a very important topicover recent years at the LHC and RHIC, producing measurements for a wide range of identified particles within the

Email addresses: zkang@physics.ucla.edu (Zhong-Bo Kang), kunsu.lee@stonybrook.edu (Kyle Lee),fanyizhao@physics.ucla.edu (Fanyi Zhao)

Preprint submitted to Elsevier May 7, 2020

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NCTS-PH/2003

Breaking the Grossman-Nir Bound in Kaon Decays

Xiao-Gang He,1, 2, ∗ Xiao-Dong Ma,1, † Jusak Tandean,1, 2, ‡ and German Valencia3, §

1Department of Physics, National Taiwan University,

No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan

2Physics Division, National Center for Theoretical Sciences,

No. 101, Sec. 2, Kuang Fu Rd., Hsinchu 300, Taiwan

3School of Physics and Astronomy, Monash University, Melbourne VIC-3800, Australia

AbstractThe ratio B(KL → π0νν)/B(K+ → π+νν) of the branching fractions of kaon decays KL → π0νν and

K+ → π+νν has a maximum of about 4.3 under the assumption that the underlying interactions change

isospin by ∆I = 1/2. This is referred to as the Grossman-Nir (GN) bound, which is respected by the

standard model (SM) and by many scenarios beyond it. Recent preliminary results of the KOTO and

NA62 Collaborations searching for these kaon modes seem to imply a violation of this bound. The KOTO

findings also suggest that B(KL → π0νν) could be much larger, by nearly two orders of magnitude, than

that predicted in the SM. In this work we study the possibility of violating the GN bound in an effective

field theory approach with only SM fields. We show that the bound holds, in addition to the original GN

scenarios, whether or not the kaon decays conserve lepton number. We demonstrate that the inclusion

of ∆I = 3/2 operators can lead to a violation of the GN bound and illustrate with an example of how

the KOTO numbers may be reached with a new physics scale of order tens of GeV.

∗Electronic address: hexg@phys.ntu.edu.tw†Electronic address: maxid@phys.ntu.edu.tw‡Electronic address: jtandean@phys.ntu.edu.tw§Electronic address: german.valencia@monash.edu

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EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)

Submitted to: Phys. Rev. Lett. CERN-EP-2020-062May 7, 2020

Dijet resonance search with weak supervisionusing √

s = 13 TeV pp collisions in the ATLASdetector

The ATLAS Collaboration

This Letter describes a search for resonant new physics using a machine-learning anomalydetection procedure that does not rely on a signal model hypothesis. Weakly supervisedlearning is used to train classifiers directly on data to enhance potential signals. The targetedtopology is dijet events and the features used for machine learning are the masses of the two jets.The resulting analysis is essentially a three-dimensional search A→ BC, for mA ∼ O(TeV),mB,mC ∼ O(100 GeV) and B,C are reconstructed as large-radius jets, without paying apenalty associated with a large trials factor in the scan of the masses of the two jets. The fullRun 2

√s = 13 TeV pp collision data set of 139 fb−1 recorded by the ATLAS detector at the

Large Hadron Collider is used for the search. There is no significant evidence of a localizedexcess in the dijet invariant mass spectrum between 1.8 and 8.2 TeV. Cross-section limits fornarrow-width A, B, and C particles vary with mA, mB, and mC . For example, when mA = 3TeV and mB & 200 GeV, a production cross section between 1 and 5 fb is excluded at 95%confidence level, depending on mC . For certain masses, these limits are up to 10 times moresensitive than those obtained by the inclusive dijet search.

© 2020 CERN for the benefit of the ATLAS Collaboration.Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license.

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adjacent halves of the left and right neighboring regions; the fit sidebands are defined as the complementof the fit signal regions. An iterative procedure is applied until the p-value from the fit sideband χ2 isgreater than 0.05. Since the NN is trained to distinguish the signal region from its neighboring regions, itis expected that the mJJ spectrum is smooth in the fit sideband region in the presence or absence of a truesignal. First, the data are fit to dn/dx = p1(1 − x)p2−ξ1p3 x−p3 , where x = mJJ/

√s, pi are fit parameters,

and the ξi are chosen to ensure that the pi are uncorrelated. If the fit quality is insufficient, an extendedfunction is used instead [101]: dn/dx = p1(1− x)p2−ξ1p3 x−p3+(p4−ξ2p3−ξ3p2) log(x). If the fit quality remainsinsufficient, a variation of the UA2 [2] fit function is tested: dn/dx = p1xp2−ξ3 e−p3x+(p4−ξ2p3−ξ3p2)x2 . If thefit quality is still insufficient, the fit sidebands are reduced by 400 GeV on both sides and the three functionsare tried again in order. This procedure is then iterated until the fit is successful. The fit results in thesignal regions for the ε = 0.1 and ε = 0.01 NN efficiency selections are presented in Figure 2. The largestpositive deviation from the fit model is 3.0σ in signal region 1, around 2500 GeV, at ε = 0.1. Globally, thepositive tail of the signal region significance distribution is consistent with a standard normal distributionat the 1.5σ level.

The W ′ signal models can be used to set limits on the production cross section of specific new particles. Toillustrate the sensitivity of the analysis to the full three-dimensional parameter space (mA,mB,mC), twomA points and multiple (mB,mC) points are selected. As the NN performance depends on the data, newnetworks are trained every time a new signal model and signal cross section are injected into the data. Inorder to reduce statistical fluctuations related to the shape of the signal, for each signal cross section thenetwork is retrained with five random samplings from the signal simulation, and the network with themedian performance is chosen. A profile-likelihood-ratio test with asymptotic formulae [110] is used todetermine 95% confidence intervals for the excluded signal cross section. The excluded cross section isreported as max(σCL, σinjected), where σCL is the cross section determined from the profile-likelihood-ratiotest and σinjected is the injected cross section. This procedure is chosen because the network’s performancemay not be as good if there were truly less signal than was injected. The resulting exclusion limits arepresented in Figure 3. As the background expectation is determined entirely from data, the only systematicuncertainty associated with the background is the statistical uncertainty from the fit. The only otherrelevant uncertainties are those related to the signal mJJ and mJ modeling; experimental uncertainties in thereconstructed jet kinematics account for about a 10% uncertainty in the excluded cross section.

The limits on W ′ production vary with mA, mB, and mC . For mB = mC = 400 GeV, the excluded crosssection is about 1 fb, a significant improvement over existing limits. Lower mB and mC result in weakerlimits because of the larger SM background in those regions; it is therefore difficult for the NN to learnto tag these signals. For some models, such as (mA,mB,mC) = (5000, 80, 80) GeV, the NN is not able toidentify the signal effectively, resulting in limits weaker than those from previous searches. For comparison,the sensitivities of the ATLAS inclusive dijet search (recast with signals from this paper) [111] andthe all-hadronic diboson resonance search [101] are also shown in Figure 3. The inclusive dijet searchsensitivity decreases for high mB and mC masses due to the use of small-radius jets that do not capture all ofthe B and C decay products. The diboson resonance search has greater sensitivity when mB,mC ≈ mW,mZ ,but it has no sensitivity away from these points. Direct searches for B and C that trigger on initial-stateradiation are also sensitive to these signal models [34–39], but the sensitivity is much weaker than 10 fb.

5

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CERN-EP-2020-068

Search for scalar and axionlike particles with the NA64 experiment

D. Banerjee,4, 5 J. Bernhard,4 V. E. Burtsev,2 A. G. Chumakov,14 D. Cooke,6 P. Crivelli∗,16 E. Depero,16

A. V. Dermenev,7 S. V. Donskov,11 R. R. Dusaev,13 T. Enik,2 N. Charitonidis,4 A. Feshchenko,2

V. N. Frolov,2 A. Gardikiotis,10 S. G. Gerassimov,3, 8 S. N. Gninenko∗,7 M. Hosgen,1 M. Jeckel,4

V. A. Kachanov,11 A. E. Karneyeu,7 G. Kekelidze,2 B. Ketzer,1 D. V. Kirpichnikov,7 M. M. Kirsanov,7

V. N. Kolosov,11 I. V. Konorov,3, 8 S. G. Kovalenko,12 V. A. Kramarenko,2, 9 L. V. Kravchuk,7

N. V. Krasnikov,2, 7 S. V. Kuleshov,12 V. E. Lyubovitskij,14, 15 V. Lysan,2 V. A. Matveev,2 Yu. V. Mikhailov,11

L. Molina Bueno,16 D. V. Peshekhonov,2 V. A. Polyakov,11 B. Radics,16 R. Rojas,15 A. Rubbia,16

V. D. Samoylenko,11 H. Sieber,16 D. Shchukin,8 V. O. Tikhomirov,8 I. Tlisova,7 D. A. Tlisov†,7 A. N. Toropin,7

A. Yu. Trifonov,14 B. I. Vasilishin,13 G. Vasquez Arenas,15 P. V. Volkov,2, 9 V. Yu. Volkov,9 and P. Ulloa12

(The NA64 Collaboration)1Universitat Bonn, Helmholtz-Institut fur Strahlen-und Kernphysik, 53115 Bonn, Germany

2Joint Institute for Nuclear Research, 141980 Dubna, Russia3Technische Universitat Munchen, Physik Department, 85748 Garching, Germany

4CERN, European Organization for Nuclear Research, CH-1211 Geneva, Switzerland5University of Illinois at Urbana Champaign, Urbana, 61801-3080 Illinois, USA

6UCL Departement of Physics and Astronomy, University College London,Gower St. London WC1E 6BT, United Kingdom

7Institute for Nuclear Research, 117312 Moscow, Russia8P.N. Lebedev Physical Institute, Moscow, Russia, 119 991 Moscow, Russia

9Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia10Physics Department, University of Patras, 265 04 Patras, Greece

11State Scientific Center of the Russian Federation Institute for High Energy Physicsof National Research Center ’Kurchatov Institute’ (IHEP), 142281 Protvino, Russia

12Departamento de Ciencias Fısicas, Universidad Andres Bello, Sazie 2212, Piso 7, Santiago, Chile13Tomsk Polytechnic University, 634050 Tomsk, Russia

14Tomsk State Pedagogical University, 634061 Tomsk, Russia15Universidad Tecnica Federico Santa Marıa, 2390123 Valparaıso, Chile

16ETH Zurich, Institute for Particle Physics and Astrophysics, CH-8093 Zurich, Switzerland

This publication is dedicated to the memory of our colleague Danila Tlisov.

We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) par-ticles that couple to two photons by using the high-energy CERN SPS H4 electron beam. Thenew particles, if they exist, could be produced through the Primakoff effect in interactions of hardbremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtualphotons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCALmodule, serving as shielding, and would be observed either through their a(s) → γγ decay in therest of the HCAL detector or as events with large missing energy if the a(s) decays downstreamof the HCAL. This method allows a substantial increase in the sensitivity to the a(s) parameterspace unexplored by previous experiments. No evidence of such processes has been found from theanalysis of the data corresponding to 2.84 × 1011 electrons on target allowing to set new limits onthe a(s)γγ-coupling strength for a(s) masses below 55 MeV.

Neutral spin-zero scalar (s) or pseudoscalar (a) massiveparticles are predicted in many extensions of the standardmodel (SM). The most popular light pseudoscalar, the

∗Corresponding author: paolo.privelli@cern.ch, sergei.gninenko@cern.ch†Deceased

axion, postulated in Refs. [1] to provide a solution ofthe ”strong CP” problem, emerges as a consequence ofthe breaking of the Peccei-Quinn (PQ) symmetry [2]. Itis now believed that the axion has a mass much smallerthan ∼ O(100) keV that was originally expected [3, 4].

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MIT-CTP/5042

Transport and hydrodynamics in the chiral limit

Eduardo Grossi,1, ∗ Alexander Soloviev,1, † Derek Teaney,1, ‡ and Fanglida Yan1, §

1Department of Physics and Astronomy,Stony Brook University, Stony Brook, New York 11794, USA

(Dated: May 7, 2020)

AbstractWe analyze the evolution of hydrodynamic fluctuations for QCD matter below Tc in the chiral

limit, where the pions (the Goldstone modes) must be treated as additional non-abelian superfluid

degrees of freedom, reflecting the broken SUL(2)×SUR(2) symmetry of the theory. In the presence

of a finite pion mass mπ, the hydrodynamic theory is ordinary hydrodynamics at long distances,

and superfluid-like at short distances. The presence of the superfluid degrees of freedom then gives

specific contributions to the bulk viscosity, the shear viscosity, and diffusion coefficients of the

ordinary theory at long distances which we compute. This determines, in some cases, the leading

dependence of the transport parameters of QCD on the pion mass. We analyze the predictions of

this computation, as the system approaches the O(4) critical point.

∗ eduardo.grossi@stonybrook.edu† alexander.soloviev@stonybrook.edu‡ derek.teaney@stonybrook.edu§ yan.fanglida@stonybrook.edu

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On the propagation of neutrinos through the Earth

M. de JongNWO-I, Nikhef, PO Box 41882, Amsterdam, 1098 DB Netherlands

Leiden University, Leiden Institute of Physics, PO Box 9504, Leiden, 2300 RA Netherlands

May 7, 2020

Abstract

The Earth is commonly used as a natural filter for the operation of deep-undergroundand deep-sea neutrino telescopes. By selecting events pointing in upward directions, thebackground of muons produced by interactions of cosmic rays in the Earth’ atmosphereabove the detector can effectively be suppressed. The corresponding neutrinos traversed alarge part of the Earth before being detected. It is commonly assumed that the neutrinosgo in a straight line through the Earth. A first study has been made of the propagation ofneutrinos through the Earth which includes the effects of the charged-current as well asneutral-current interactions. It is found that the diffusion of neutrinos due toneutral-current interactions leads to an increase of the detectable flux of neutrinos.

1 Introduction

The cross-section of neutrinos to interact with normal matter is known to be very smallcompared to that of other elementary articles. This makes it relatively difficult to detectneutrinos. On the other hand, it is possible to filter neutrinos by employing a sufficiently thicklayer of matter. For the operation of neutrino telescopes such as IceCube and KM3NeT, theEarth is used a a natural filter for the detection of high-energy neutrinos (1 TeV− 1 PeV) fromthe cosmos [4, 5]. By selecting events pointing in upward directions (i.e. by looking downward),the background of muons produced by interactions of cosmic rays in the Earth’ atmosphereabove the detector can effectively be suppressed. The corresponding neutrinos traversed a largepart of the Earth before being detected. For the interpretation of the data, it is thus importantto know how a flux of neutrinos is affected by the propagation of neutrinos through the Earth.In the following, the cross-section of neutrinos to interact with matter is taken from reference[2]. Up to energies of 1 TeV or so, the cross-section is so small that (almost) all neutrinos passthrough the Earth unhampered. As a function of energy, however, the cross-section steadilyincreases. As a consequence, (almost) all neutrinos interact on their way through the Earth atenergies in excess of a few PeV. The interaction of a neutrino in the Earth is usuallyinterpreted as absorption, thereby leaving a finite energy window to observe neutrinos from theother side of the Earth. This limitation can partly be overcome by also selecting horizontally oreven downward traveling neutrinos which comes with the cost of a (much) larger background.

Neutrinos can interact with matter via the so-called charged-current or neutral-currentinteraction in which a W± or Z boson is exchanged with a nucleon in the Earth, respectively. Inthe first, the neutrino is transformed into a corresponding charged lepton. With the exceptionof the τ -lepton, the charged lepton usually stops in the Earth before reaching the detector

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OU-HET 1058

Deep Learning and AdS/QCD

Tetsuya Akutagawa,∗ Koji Hashimoto,† and Takayuki Sumimoto‡

Department of Physics, Osaka University,Toyonaka, Osaka 560-0043, Japan

We propose a deep learning method to build an AdS/QCD model from the data of hadron spectra.A major problem of generic AdS/QCD models is that a large ambiguity is allowed for the bulk gravitymetric with which QCD observables are holographically calculated. We adopt the experimentallymeasured spectra of ρ and a2 mesons as training data, and perform a supervised machine learningwhich determines concretely a bulk metric and a dilaton profile of an AdS/QCD model. Our deeplearning (DL) architecture is based on the AdS/DL correspondence [1] where the deep neural networkis identified with the emergent bulk spacetime.

I. INTRODUCTION

The AdS/CFT correspondence [2–4], or the holo-graphic principle, is a promising way to define a quantumgravity. In spite of its importance, a fatal problem is tofind a dual gravity system for a given QFT, for whichso far no systematic approach has been successful. Par-ticularly important QFTs are those with Yang-Mills sec-tors, including QCD, whose large N and strong couplinglimit are believed to give a classical gravity dual, whilewe are lacking in how to construct the dual concretelyand explicitly. So far, we know necessary conditions forthe gravity dual, such as symmetries and spectral prop-erties, as well as recently investigated OTOCs [5–7] andcomputational complexities [8].

The string theory “top-down” construction does notsolve the problem, because it merely provides examplesas a pair of a gravity and a QFT at the same time. Manyexcellent work provided a pair in which the QFT sideresembles a given target QFT. A lot of effort has beenput to seek for a gravity dual of QCD, as QCD is therenowned, and realistic QFT among all.

It should be emphasized that once a classical gravitysystem is given, the dual QFT quantities can be easilycalculated by the AdS/CFT dictionary. The problem ishow we can go backwards: for a given QFT correlators,how we get the gravity system. To solve this kind ofinverse problems, we need special techniques. In partic-ular, strongly coupled QFT consists of a vast amountof data, such as n-point correlators for infinite kinds oflocal/nonlocal gauge invariant operators. Furthermore,QCD is a part of the Standard Model for which a lotof experimental data is available. To this end, machinelearning method may help us. If there exists a gravitydual of QCD which is simple enough with a finite numberof parameters, the features of the data of QCD needs tobe efficiently extracted, by solving the AdS/CFT back-wards. Deep learning [9–11] which technically advanced

∗ akutagawa@het.phys.osaka-u.ac.jp† koji@phys.osaka-u.ac.jp‡ t sumimoto@het.phys.osaka-u.ac.jp

these years may shed light on the fatal problem of theAdS/CFT.

In Ref. [1], deep learning was applied to determine anemergent gravity metric from a given data of a QFT.The dictionary used was for a one-point function of anoperator in the QFT, corresponding to a bulk field valuein the dual gravity system. In Ref. [12], the method wasapplied to lattice QCD data of a chiral condensate, to finda metric of the gravity system dual to QCD. Based on thesuccess of this method working for one-point functions, inthis paper we make one more step toward realistic QCD.We use hadronic two-point functions, i.e. the hadronspectra which are measured in experiments.

Needless to say, the most well-observed quantities inexperiments for QCD are hadron spectra and hadroncouplings. The best framework to test the deep learn-ing method is the AdS/QCD [13–15], a bottom-up con-struction of phenomenological gravity models based onsymmetries and the dictionary. It is known that the sim-ple AdS/QCD framework can host lots of QCD quan-tities including hadron spectra. Here, again, the con-ventional methods in the AdS/QCD is first to come upwith a gravity model, then to calculate the QCD quan-tities from the model and then to compare those withexperimental data. If the quantity does not match well,one throws away the gravity model and try again with adifferent gravity model. The gravity model has a largearbitrariness, and in addition the dictionary is nonlocal,so solving the inverse problem is challenging. This is thereason why the deep learning method can help findingthe gravity dual of QCD.

The AdS/DL correspondence in Ref. [1] was inventeddue to the similarity between the deep neural network(DNN) and bulk gravity system.1 In the training, weightsof the neural network are trained and determined by ma-chine, which is regarded as an emergence of the space-time, as the differential equation on the discretized grav-ity spacetime is regarded as a propagation of information

1 For a detailed relation, see Ref. [16]. An early study on thesimilarity between the AdS/CFT and the DL is in Ref. [17]. SeeRefs. [18, 19] for related essays. A continuum limit of the deeplayers was studied in a different context [20].

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Prepared for submission to JHEP

The Smallest SU(N) Hadrons

Stefano Profumoa,b

aDepartment of Physics, University of California, 1156 High St, Santa Cruz, CA 95064, USAbSanta Cruz Institute for Particle Physics, University of California, 1156 High St, Santa Cruz,CA 95064, USA

E-mail: profumo@ucsc.edu

Abstract: If new physics contains new, heavy strongly-interacting particles belonging toirreducible representations of SU(3) different from the adjoint or the (anti)fundamental, it isa non-trivial question to calculate what is the minimum number of quarks/antiquarks/gluonsneeded to form a color-singlet bound state (“hadron”) with the new particle. Here, I provethat for an SU(3) irreducible representation with Dynkin label (p, q), the minimal numberof quarks needed to form a product that includes the (0,0) representation is 2p + q. Igeneralize this result to SU(N), with N > 3. I also calculate the minimal total number ofquarks/antiquarks/gluons that, bound to a new particle in the (p, q) representation, givea color-singlet state: ng = b(2p + q)/3c gluons, nq = b(2p + q − 3ng)/2c antiquarks, andnq = 2p+ q− 3ng− 2nq quarks (with the exception of the 6∼(0,2) and of the 10∼(0,3), forwhich 2 and 3 quarks, respectively, are needed to form the most minimal color-less boundstate). Finally, I show that the possible values of the electric charge QH of the smallesthadron H containing a new particle X in the (p, q) representation of SU(3) and with electriccharge QX are −(2p+ q)/3 ≤ QH −QX ≤ 2(2p+ q)/3.

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Evading the Grossman-Nir bound with ∆I = 3/2 new physics

Xiao-Gang He,1, 2, ∗ Xiao-Dong Ma,1, † Jusak Tandean,1, 2, ‡ and German Valencia3, §

1Department of Physics, National Taiwan University,

No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan

2Physics Division, National Center for Theoretical Sciences,

No. 101, Sec. 2, Kuang Fu Rd., Hsinchu 300, Taiwan

3School of Physics and Astronomy, Monash University, Melbourne VIC-3800, Australia

AbstractRare kaon decays with missing energy, K → π+Emiss, have received considerable attention because

their rates can be calculated quite precisely within the standard model (SM), where the missing energy is

carried away by an undetected neutrino-antineutrino pair. Beyond the SM, clean theoretical predictions

can also be made regarding these processes. One such prediction is the so-called Grossman-Nir (GN)

bound, which states that the branching fractions of the KL and K+ modes must satisfy the relation

B(KL → π0+Emiss) . 4.3B(K+ → π++Emiss) and applies within and beyond the SM, as long as the

hadronic transitions change isospin by ∆I = 1/2. In this paper we extend the study of these modes

to include new-physics scenarios where the missing energy is due to unobserved lepton-number-violating

neutrino pairs, invisible light new scalars, or pairs of such scalars. The new interactions are assumed to

arise above the electroweak scale and described by an effective field theory. We explore the possibility of

violating the GN bound through ∆I = 3/2 contributions to the K → π transitions within these scenarios

and find that large violations are only possible in the case where the missing energy is due to an invisible

light new scalar.

∗Electronic address: hexg@phys.ntu.edu.tw†Electronic address: maxid@phys.ntu.edu.tw‡Electronic address: jtandean@phys.ntu.edu.tw§Electronic address: german.valencia@monash.edu

1

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Axion-like-particle generation by laser-plasma interaction

Shan Huang (黄杉),1, 2 Baifei Shen (沈百飞),1, 3, ∗ Zhigang Bu (步志刚),1 Xiaomei

Zhang (张晓梅),1, 3 Liangliang Ji (吉亮亮),1 and Shuhua Zhai (翟树华)1, 2, †

1State Key Laboratory of High Field Laser Physics,

Shanghai Institute of Optics and Fine Mechanics,

Chinese Academy of Sciences, Shanghai 201800, China

2University of Chinese Academy of Sciences, Beijing 100049, China

3Department of Physics, Shanghai Normal University, Shanghai 200234, China

(Dated: May 7, 2020)

Abstract

Axion, a hypothetical particle that is crucial to quantum chromodynamics and dark matter

theory, has not yet been found in any experiment. With the improvement of laser technique, a

much stronger quasi-static electromagnetic field can be created in laboratory via laser-plasma in-

teraction. In this article, we discuss the feasibility of axion’s exploring experiment using planar

and cylindrically symmetric laser-plasma field as background while probing with an ultrafast su-

perstrong laser or an x-ray free-electron laser with high photon number. Compared to classical

magnet design, the axion source in laser-plasma interaction trades the accumulating length for the

source’s interacting strength. Besides, a structured field in the plasma creates a tunable transverse

profile of the interaction and improves the signal-noise ratio via the mechanisms such as phase-

matching. We give some simple layouts and estimate detectable parameters like axion production

and probe’s polarization rotation, which reveals the possibility of future laser-plasma axion source

in laboratory.

∗ Correspondence: bfshen@mail.shcnc.ac.cn† Currently: ELI-Beamlines, the Czech Republic

1

The global geometrical property of jet events in high-energy nuclear collisions

Shi-Yong Chen,1 Wei Dai ∗,2 Shan-Liang Zhang,1 Qing Zhang,1 and Ben-Wei Zhang †1, 3

1Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics,Central China Normal University, Wuhan 430079, China

2School of Mathematics and Physics, China University of Geosciences, Wuhan 430074, China3Institute of Quantum Matter, South China Normal University, Guangzhou 510006, China

(Dated: May 7, 2020)

We present the first theoretical study of medium modifications of the global geometrical pat-tern, i.e., transverse sphericity (S⊥) distribution of jet events with parton energy loss in relativisticheavy-ion collisions. In our investigation, POWHEG+PYTHIA is employed to make an accuratedescription of transverse sphericity in the p+p baseline, which combines the next-to-leading order(NLO) pQCD calculations with the matched parton shower (PS). The Linear Boltzmann Transport(LBT) model of the parton energy loss is implemented to simulate the in-medium evolution of jets.We calculate the event normalized transverse sphericity distribution in central Pb+Pb collisions atthe LHC, and give its medium modifications. An enhancement of transverse sphericity distributionat small S⊥ region but a suppression at large S⊥ region are observed in A+A collisions as comparedto their p+p references, which indicates that in overall the geometry of jet events in Pb+Pb becomesmore pencil-like. We demonstrate that for events with 2 jets in the final-state of heavy-ion colli-sions, the jet quenching makes the geometry more sphere-like with medium-induced gluon radiation.However, for events with ≥ 3 jets, parton energy loss in the QCD medium leads to the events morepencil-like due to jet number reduction, where less energetic jets may lose their energies and thenfall off the jet selection kinematic cut. These two effects offset each other and in the end result inmore jetty events in heavy-ion collisions relative to that in p+p.

I. INTRODUCTION

Heavy ion collision experiments performed at theRHIC and the LHC are designed to study the propertiesof the de-confined Quark Gluon Plasma (QGP) whichcreated shortly after these collisions [1–7]. Energetic par-tons produced at the initial collision will traverse throughthis hot and dense medium and lose their energies by in-teracting with such medium, it is referred as jet quench-ing effect [8–10]. This phenomenon can be quantifiedby various observables, from single hadron productionsuppression RhAA [11–18] to the observables within the

productions of full jets such as inclusive jets RjetAA, dijetsmomentum imbalance AJ , and tagged jets momentumimbalance zJ , the angular correlations of the leading twojets ∆Φ12 etc. The available of these full jets observablesare due to the improvement of jet finding algorithm andjet reconstruction in the final state of the heavy ion col-lisions at the LHC. The study of these observables aremainly focused on the medium modifications of individ-uals or the leading two jets in the final state of collisionevents [19–44]. It is of great interest to investigate theimpact of the jet quenching effect to the whole picture ofproduced events with all the reconstructed jets in them.For such investigation, observables that can characterizethe global geometrical properties of the produced eventsare required, and the medium alteration of these observ-ables in A+A collisions might give insights into the mech-anism of the jet quenching phenomenon or even provide

∗weidai@cug.edu.cn†bwzhang@mail.ccnu.edu.cn

further constraint on jet quenching modeling.

Event shape observables, named as thrust, sphericity,have long been proposed to study geometrical proper-ties and patterns of the energy flow of the collisions,and thus provide a probe of multi-jet topologies in aninteraction [46–59]. For example, the sphericity of anevent was firstly proposed to confirm the jet hypothesisfor hadron production in electron-positron collisions byG. Hanson and his collaborators at 1975 [45]. Recently,experimentalists show interests of the event shape ob-sverables at large momentum transfer, ATLAS Collabo-ration at the LHC has measured the production distri-bution of the transverse sphericity (S⊥) in p+p collisionsat√s = 7 TeV [58]. The larger transverse sphericity S⊥

is, the more isotropic an event is.

In this manuscript, for the first time, we calculate themedium modification of the global geometrical property,i.e. the transverse sphericity distribution in Pb+Pb colli-sions at the LHC, by including jet quenching effect in theQGP. We found the event normalized S⊥ distributions inPb+Pb collisions are enhanced at very small S⊥ regionwhile suppressed at larger S⊥ compared to the distribu-tion in p+p reference, indicating more proportion of thesurvived events are shifted to pencile-like region (smallS⊥) due to the jet quenching effect. It is however coun-terintuitive. To understand such a result, we first studiedthe nuclear modifications of S⊥ distributions for eventswith identical numbers of jets. Next, the reduction of jetnumbers in events due to the jet energy loss effect dur-ing the in-medium evolution are therefore investigated.It happens when jets are discarded because their pT fallbelow the lower threshold of the jet selection. We furtherinvestigate the medium modification of the azimuth anglecorrelation (∆φ) and transverse momentum balance (xJ)

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Tau decay into ντand a1(1260), b1(1235), and two K1(1270)

L. R. Dai∗

School of Science, Huzhou University, Huzhou 313000, Zhejiang, China

Department of Physics, Liaoning Normal University, Dalian 116029, China and

Departamento de Fısica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC,

Institutos de Investigacıon de Paterna, Aptdo. 22085, 46071 Valencia, Spain

L. Roca†

Departamento de Fısica, Universidad de Murcia, E-30100 Murcia, Spain

E. Oset‡

Departamento de Fısica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC,

Institutos de Investigacıon de Paterna, Aptdo. 22085, 46071 Valencia, Spain

(Dated: May 7, 2020)

We study the τ → ντA decay, with A an axial-vector meson. We produce the a1(1260) andb1(1235) resonances in the Cabibbo favored mode and twoK1(1270) states in the Cabibbo suppressedmode. We take advantage of previous chiral unitary approach results where these resonances appeardynamically from the vector and pseudoscalar meson interaction in s-wave. Actually two differentpoles were obtained associated to the K1(1270) quantum numbers. We find that the unmeasuredrates for b1(1235) production are similar to those of the a1(1260) and for the two K1 states wesuggest to separate the present information on the Kππ invariant masses into K∗π and ρK modes,the channels to which these two resonances couple most strongly, predicting that these modes peak atdifferent energies and have different widths. These measurements should shed light on the existenceof these two K1 states.

PACS numbers:

I. INTRODUCTION

Tau decays, with about 65 % branching fraction intohadronic channels [1], (being the τ the only lepton withenough mass to decay into hadrons), have proved to bea good tool to learn about strong interactions at lowenergies [2–5]. In particular, some of the decay modeshave one resonance in the final state and we are con-cerned about the production of particular resonanceswhich stand for a molecular interpretation. Concretely,in this work we are concerned about the production ofaxial vector resonances, A, this is, τ → ντA. Giventhat in the τ → ντ qq at the quark level, the quarksare du for the Cabibbo favored process, this defines thehadronic state with isospin I = 1. Hence, we can ob-tain the a1(1260) (1

−(1++)) and the b1(1235) (1+(1+−)).

For Cabibbo suppressed processes the initial quark stateis su and hence we produce a state with I = 1/2 andstrangeness. This is the K1(1270) (1/2(1/2+)). An is-sue we wish to raise in this work is the fact that thechiral theories for the axial-vector mesons predict twostates for K1(1270) [6, 7] and we evaluate the rates fordecay into either state and suggest the way to differ-entiate the two states in experiment. In chiral unitarytheory, the axial vector mesons are generated from the

∗dailianrong68@l26.com†luisroca@um.es‡oset@ific.uv.es

interaction of vector mesons with pseudoscalars [6, 8, 9].The production of an axial-vector meson in the tau de-cay proceeds then in the following way: all possible pairsof vector-pseudoscalar are produced and then they areallowed to interact among themselves, and in this pro-cess the resonances are generated, decaying later on invector-pseudoscalar pairs or other channels. From themicroscopical point of view this is done from the originalqq pair creation by means of hadronization, where an ex-tra qq pair is created with the quantum numbers of thevacuum. A technical way to implement this step is donein Ref. [10] using the 3P0 model [11–13] and we shall usesome results from this work here.

In the literature there are many works dealing withthe production of vector-pseudoscalar in tau decays us-ing different approaches. In Refs. [14, 15] vector mesondominance is used while in Refs. [16–23] the Nambu JonaLasinio model (NJL) [24] is used. In those works theaxial resonances when suited, are introduced explicitlyvia amplitudes dictated by symmetries [14, 15] or withexplicit coupling to quarks in the NJL model. This isdifferent to our approach, since what we do is producethe vector-baryon pairs and then, using chiral dynamicsand coupled channels Bethe Salpeter equations the pairsare allowed to interact and the interaction generates theaxial-vector resonances, which are implicit in the scatter-ing amplitudes used.

The τ → ντa1(1260) has been studied as part of theτ → ντπ

+π−π−, which has had a wide attention exper-imentally [25–30]. While the a1(1260) production pro-vides the main contribution to the process, other mech-

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EPJ manuscript No.(will be inserted by the editor)

Description of the newly observed Ξ0cstates as molecular states

HongQiang Zhu1, NaNa Ma2, and Yin Huang3a

1 College of Physics and Electronic Engineering, Chongqing Normal Universit2 School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, People’s Republic of China3 School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031,China

Received: date / Revised version: date

Abstract. Very recently, three new structures Ξc(2923)0, Ξ(2938)0, and Ξ(2964)0 at the invariant mass

spectrum of Λ+c K

− observed by the LHCb Collaboration triggers a hot discussion about their inner struc-ture. In this work, we study the strong decay mode of the newly observed Ξc assuming that the Ξc is aDΛ − DΣ molecular state. With the possible quantum numbers Jp = 1/2± and 3/2±, the partial decaywidths of the DΛ− DΣ molecular state into the Λ+

c K−, Σ+

c K−,and Ξ+c π− final states through hadronic

loop are calculated with the help of the effective Lagrangians. By comparison with the LHCb observation,the current results of total decay width support the Ξ(2923)0 as DΛ− DΣ molecule while the decay widthof the Ξc(2938)

0 and Ξ(2964)0 can not be well reproduced in the molecular state picture. In addition, thecalculated partial decay widths with S wave DΛ− DΣ molecular state picture indicate that allowed decaymodes, Ξ+

c π−, may have the biggest branching ratios for the Ξc(2923). The experimental measurementsfor this strong decay process could be a crucial test for the molecule interpretation of the Ξc(2923).

PACS. 13.60.Le decay widths – 13.85.Lg mass spectrum – 25.30.-c molecular state

1 Introduction

During the past several decades, many narrow baryonswith a heavy charm quark, a light up or down quark, anda strange quark have been reported by the LHCb,CDFCollaboration and so on [1]. Very recently, three otherneutral resonances Ξ∗0

c named Ξc(2923)0, Ξc(2939)

0, andΞc(2965)

0 have been observed in the K−Λ+c mass spectra

by the LHCb Collaboration [2]. The observed resonancemasses and widths are

M = 2923.04± 0.25(stat)± 0.20(syst)± 0.14(Λ+c ) MeV

Γ = 7.1± 0.8(stat)± 1.8(syst) MeV,

M = 2938.55± 0.21(stat)± 0.17(syst)± 0.14(Λ+c ) MeV

Γ = 10.2± 0.8(stat)± 1.1(syst) MeV,

M = 2964.88± 0.26(stat)± 0.14± (syst)0.14(Λ+c ) MeV

Γ = 14.1± 0.9(stat)± 1.3(syst) MeV,

respectively. From the observed decay mode, the isospinof these three states are 1/2. Although the quantum num-bers of these states remain undetermined, it is very helpfulto understand the spectroscopy of the heavy baryons con-taining c and s quark.

aEmail address: huangy2019@swjtu.edu.cn

Due to their observed decay mode, the new structuresΞc(2923)

0, Ξ(2938)0, and Ξ(2964)0 contain at least threedifferent valence quark components. In other word, thesestates may be candidates of conventional three-quark state.Indeed, the QCD sum rule suggests that the newly ob-served states Ξc(2923)

0, Ξ(2938)0, and Ξ(2964)0 are most

likely to be considered as the P -wave Ξ′

c baryons with thespin-parity Jp = 1/2− or Jp = 3/2− [3]. In Ref. [4] theΞc(2923)

0, Ξ(2938)0, and Ξ(2964)0 ware suggested to be

1P Ξ′

c state with spin-parity JP = 3/2− or JP = 5/2−

in the chiral quark model. In Ref. [5] the two-body strongdecays of the Ξc(2923)

0, Ξ(2938)0, and Ξ(2964)0 werecalculated by employing the 3P0 approach with the con-clusion that the Ξc(2923)

0 and Ξ(2938)0 can be 1P Ξ′

c

states, and the Ξ(2964)0 can be regarded as the 2S Ξ′

cstate. The lattice QCD calculation was also performedand try to determine their quantum numbers [6].

Although the authors in Refs. [3,4,5,6] try to assignthese states into the conventional three-quark frames, it isobvious that the inner structure of Ξc(2923)

0, Ξ(2938)0,and Ξ(2964)0 are not finally determined. And anotherinterpretation is treating them as DΛ − DΣ molecularstates, because the smallest mass gaps between the newlyobserved Ξc baryons and the ground Ξc, about 450 MeV,is large enough to excite a light quark-antiquark pair toform a hadronic molecular. Indeed, it is shown in Refs. [7,8,9] that the interaction between D meson and Λ or Σ

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Potential Model for Σ−uHybrid Meson State

Nosheen Akbar∗ and Saba Noor†

∗Department of Physics, COMSATS University Islamabad, Lahore Campus,Lahore(54000), Pakistan.

†Centre For High Energy Physics, University of the Punjab, Lahore(54590), Pakistan.

Abstract

In this paper, lattice simulations are used to propose a potential model for gluonic excitedΣ−

ustates of bottomonium meson . This proposed model is used to calculate radial wave

functions, masses and radii of Σ−

ubottomonium hybrid mesons. Here, gluonic field between

a quark and an antiquark is treated as in the Born-Oppenheimer expansion, and Schrodingerequation is numerically solved employing shooting method. Results of calculated masses forΣ−

ustate are in quite good agreement with the lattice simulations.

Keywords: Meson, gluonic excitations, Potential model, QCD

I. INTRODUCTION

Static quark potential models play important role in the understanding of Quantum chromo-dynamics. A hybrid static potential is defined as a potential of a static quark-antiquark pairwith the gluonic field in the excited states. These hybrid static potentials for different statesof mesons are computed in refs. [1][2][3][4][5]. Hybrid static potentials are characterized byquantum numbers, Λ, η, and ǫ, where Λ is the projection of the total angular momentum ofgluons and for Λ = 0,±1,±2,±3, ...., meson states are represented as Σ,Π,∆ and so on [1]. η isthe combination of parity and charge and for η = P ◦C = +,−, states are labelled by sub-scriptg, u [1]. ǫ is the eigen value corresponding to the operator P and is equal to +,−. Parity andcharge for hybrid static potentials are defined as [1]

P = ǫ(−1)L+Λ+1, C = ǫη(−1)L+Λ+S , (1)

The low-lying static potential states are labelled as Σ+g ,Σ

−g ,Σ

+u ,Σ

−u ,Πg,Πu,∆g,∆u and so on[1].

Σ+g is the low-lying potential state with ground state gluonic field and is approximated by a

coulomb plus linear potential. The Πu and Σ−u are the QQ potential states with low lying

gluonic excitations. Linear plus coulombic potential model is extended in [6] for Πu states byfitting the suggested ansatz with lattice data[5] and the extended model is tested by findingproperties of mesons for a variety of JPC states in refs.[6, 7, 8, 9]. In this Paper, linear pluscoulombic potential model is extended for lowest excited hybrid state, Σ−

u by fitting the latticedata [1] with the suggested analytical expression (ansatz). The validity of suggested ansatzis tested by calculating the spectrum of Σ−

u states and comparing it with lattice results. Forthis purpose, Born-Oppenheimer formalism and adiabatic approximation is used. Relativisticcorrections in the masses are incorporated through perturbation theory.

∗e mail: nosheenakbar@cuilahore.edu.pk,noshinakbar@yahoo.com†e mail: sabanoor87@gmail.com

1

Role of transverse gluon in SSA

G.P. Zhang∗

Department of physics, Yunnan University, Kunming, Yunnan 650091, China

It is known the single transverse spin asymmetry in semi-inclusive deep inelastic scattering can befactorized by a twist-3 distribution function TF , which contains a gluon field strength tensor. Withtransverse gluon included in the power expansion, we find the gluon field strength tensor can berecovered definitely in soft-gluon-pole contribution at leading order of αs expansion. This conclusionholds in Feynman and light-cone gauges.

I. INTRODUCTION

The single transverse spin asymmetry(SSA) in high-PT pion production is discovered in 70’s[1], and the asymmetryis of order 10%. A possible explanation in perturbative QCD for this large asymmetry is Efremov-Teryaev-Qiu-Sterman(ETQS) mechanism, which has been proposed for many years[2],[3]. In this mechanism, SSA is proportionalto ETQS matrix element, which is a correlation function of quark and gluon fields defined on light-cone. How to obtainthe twist-3 hard coefficients before ETQS matrix element has been discussed thoroughly in literatures. One of theremaining problems is how to recover gluon field strength tensor appearing in ETQS matrix element consistently. Aclear algorithm to get the twist-3 hard coefficients is first given by Qiu and Sterman[3], in which the subcross section iscalculated by taking the initial coherent gluon as a longitudinal gluon G+ with a small transverse momentum k⊥, then,the subcross section is expanded to O(k⊥). After the proof that only the matrix element 〈ψ(∂ρ⊥G

+)ψ〉 appears after

transverse momentum expansion, the ETQS matrix element TF then is obtained by the replacement ∂ρ⊥G+ → −G+ρ

⊥ ,

where G+ρ⊥ is gluon field strength tensor. This replacement is applied in almost all following works, see for example

[4–9]. In [10–15]even loop correction is calculated in this formalism, and the twist-3 factorization formula is justifiedat one-loop level. Thus, this algorithms is reliable to give correct answer. But, since the contribution of G⊥ is notcalculated, there is still a problem whether the contribution of G⊥ can be incorporated into ETQS matrix element.For a complete calculation, one has to also calculate the contribution of G⊥ and to see whether the combination∂ρ⊥G

+ − ∂+Gρ⊥ appears. This problem is studied by Eguchi, Koike and Tanaka in[16], where a group of consistence

relations are derived in order to make sure gluon field strength tensor G+ρ⊥ is correctly(completely) reproduced. For

hard-gluon-pole and soft-fermion-pole contributions, these conditions are satisfied easily due to Ward Identities, andit is confirmed that G⊥ expansion gives the same hard coefficients as that obtained from G+ expansion. However,for soft-gluon-pole(SGP) contribution, although the conditions are satisfied by analyzing the detailed cancellationbetween mirror diagrams, a direct calculation based on G⊥ expansion is still missing. For this reason how to obtainSGP in light-cone gauge is not described in [16] either. It is argued that G⊥ contribution contains some ambiguitiesand some hard coefficients may be lost due to xδ(x) = 0. The analysis of [16] is very clear and thorough. But,as we will show in this paper, G⊥ expansion is definite and gives the same hard coefficients as that obtained fromG+ expansion. The price for using G⊥ expansion is one has to incorporate the contribution from another twist-3distribution function q∂(x), besides ETQS matrix element TF (x, x). Also, the coefficient of q∂(x) can be determineddefinitely. As an example, we will consider the SSA for high PT pion production in semi-inclusive deep inelasticscattering(SIDIS), which is considered in [8],[9],[16]. The generalization of this proof to other processes is not difficult.The paper is organized as follows: In Sec.II, our notations and the kinematics of SIDIS are introduced; In Sec.III,the calculation including G⊥ expansion is performed and how to get the gluon fields strength tensor G+ρ

⊥ is shownexplicitly, and a formula is given for the corresponding hard coefficients; In Sec.IV, the explicit expressions of hardcoefficients for quark and gluon fragmentations are given; In Sec.V, we shortly discuss the generalization of our proofto higher orders of αs expansion and make a summary.

∗ gpzhang@ynu.edu.cn

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Chiral molecules as sensitive probes for direct detection of P-odd cosmic fields

Konstantin Gaul,1 Mikhail G. Kozlov,2, 3 Timur A. Isaev,2 and Robert Berger1

1Fachbereich Chemie, Philipps-Universitat Marburg,Hans-Meerwein-Straße 4, 35032 Marburg, Germany

2Petersburg Nuclear Physics Institute of NRC “Kurchatov Institute”, Gatchina 188300, Russia3St. Petersburg Electrotechnical University “LETI”, Prof. Popov Str. 5, 197376 St. Petersburg

(Dated: May 7, 2020)

Particular advantages of chiral molecules for direct detection of the time-dependence of pseu-doscalar and the timelike-component of pseudovector cosmic fields are highlighted. Such fields areinvoked in different models for cold dark matter or in the Lorentz-invariance violating standardmodel extensions and thus are signatures of physics beyond the standard model. The sensitivity ofa twenty year old experiment with the molecule CHBrClF to pseudovector cosmic fields as charac-terized by the parameter |be0| is estimated to be O(10−12 GeV) and allows to predict the sensitivityof future experiments with favorable choices of chiral molecular probes to be O(10−17 GeV), whichwill be an improvement of the present best limits by at least two orders of magnitude.

Introduction.—The nature of dark matter (DM), theexistence of which is invoked to explain the cosmologi-cal motion of visible matter, is considered to be one ofthe biggest unsolved problems of modern physics (see e.g.Ref. [1]). Among the various DM theories, the cold DM(CDM) variant appears to provide a simple explanationfor a wealth of astrophysical observations [2]. Up to now,however, the constituents of CDM are unknown and canrange from macroscopic objects such as black holes tonew particles like weakly interacting massive particles(WIMPs), axions, sterile neutrinos or dark photons (seee.g. Refs. [3–5]).

The model of CDM has also several shortcomings [6–11]. In order to overcome some of these, so-called fuzzyCDM models, which assume CDM to consist of ultra lightparticles with masses of mφ ∼ 1× 10−22 eV/c2, were pro-posed [12, 13].

CDM candidates are different types of weakly interact-ing particles (an overview can be found e.g. in Ref. [14]).Among those, we focus in the following on pseudoscalarand pseudovector particles as they are a source of directparity (P) violation.

Pseudoscalar CDM particles behave as axions, whichwere originally proposed [15–17] as a solution to the so-called strong CP-problem [18], i.e. the apparently miss-ing CP-violation in quantum chromodynamics (QCD) al-though there is a free parameter in QCD that can ac-count for such a violation. The window to search forsuch particles can be restricted to a defined parameterspace, like for the QCD axion (see e.g. [19]) which hasto solve the strong CP-problem, or can be large as foraxionic particles that are not bound to solve the strongCP-problem. The latter are often referred to as axion-like particles (ALPs). Pseudovector fields are importantfor models such as dark photons [20, 21] and also ap-pear as sources of local Lorentz invariance violation inthe Standard Model Extension (SME) [22].

In the last decade many proposals for new experimentsand improved bounds on pseudoscalar CDM appeared,some of which employ atomic spectroscopy (see e.g. [23–28]). Among the latter, direct measurement of parity vio-

lation with modern atomic precision spectroscopy [26, 29]provided strict limits on static P-odd fields, where effectsof these fields adds to parity violating effects stemmingfrom electroweak electron-nucleus interactions mediatedby the Z0 boson.

It is well known that such P-odd effects are stronglyenhanced in chiral molecules, as the chiral arrangementof the nuclei leads to helicity in the electron cloud (seee.g. Refs. [30, 31]). This effect can be measured as en-ergy difference between enantiomers of chiral moleculesor as resonance frequency differences between the twonon-identical mirror-image molecules [32, 33]. As fre-quency shifts can be measured very accurately, this ap-pears to be a particularly promising tool to search forP-odd cosmic fields (for recent reviews on molecular par-ity violation see [30, 31, 34–38]). In the following weshow advantages of the use of chiral molecules to searchfor P-odd cosmic fields. We estimate the sensitivity oncosmic parity violation of a twenty year old experiment[39] with the chiral methane derivative CHBrClF [40, 41]and discuss the prospects of modern experiments withchiral molecules.Theory.—We write the pseudoscalar cosmic field as

φ(t) = φ0 cos(ωφt) (see e.g. Ref. [29]), which is sup-posed to behave non-relativistically ~ωφ ≈ mφc

2. Theinteraction of electrons ψe with such pseudoscalar fieldsφ(t) can be described by the following Lagrangian density(see e.g. [16, 17])

Lφps = gφee(~c ∂µφ)ψeγµγ5ψe , (1)

where gφee is a coupling constant of dimension GeV−1.Here the 4× 4 Dirac matrices are defined as

γ0 =

(12×2 02×2

02×2 −12×2

), γk =

(02×2 σk

−σk 02×2

), (2)

where σk are the Pauli spin matrices with upper indicesk = 1, 2, 3. The index µ runs as µ = 0, 1, 2, 3. We defineγ5 = ıγ0γ1γ2γ3 with ı =

√−1 being the imaginary

unit. ∂µ = ∂∂xµ is the first derivative with respect to the

four-vector xµ = (ct, x, y, z) and we use Einstein’s sum

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CERN-TH-2020-069

Heavy quark diffusion in an overoccupied gluon plasma

K. Boguslavski,1 A. Kurkela,2, 3 T. Lappi,4, 5 and J. Peuron6

1Institute for Theoretical Physics, Technische Universitat Wien, 1040 Vienna, Austria2Theoretical Physics Department, CERN, Geneva, Switzerland

3Faculty of Science and Technology, University of Stavanger, 4036 Stavanger, Norway4Department of Physics, P.O. Box 35, 40014 University of Jyvaskyla, Finland

5Helsinki Institute of Physics, P.O. Box 64, 00014 University of Helsinki, Finland6European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) and Fondazione Bruno Kessler,

Strada delle Tabarelle 286, I-38123 Villazzano (TN), Italy

We extract the heavy-quark diffusion coefficient κ and the resulting momentum broadening 〈p2〉 ina far-from-equilibrium non-Abelian plasma. We find several features in the time dependence of themomentum broadening: a short initial rapid growth of 〈p2〉, followed by linear growth with time dueto Langevin-type dynamics and damped oscillations around this growth at the plasmon frequency.We show that these novel oscillations are not easily explained using perturbative techniques butresult from an excess of gluons at low momenta. These oscillation are therefore a gauge invariantconfirmation of the infrared enhancement we had previously observed in gauge-fixed correlationfunctions. We argue that the kinetic theory description of such systems becomes less reliable in thepresence of this IR enhancement.

I. INTRODUCTION

Transport coefficients, such as viscosities, diffusion co-efficients and conductivities contain information aboutmicroscopic properties of the medium. In the frameworkof QCD matter produced in ultrarelativistic heavy-ioncollisions, the evaluation of such transport coefficientshas been a longstanding problem. Perturbative evalua-tions at Leading Order (LO) have been available for along time [1–3]. More recently perturbative calculationshave been pushed to next-to-leading order (NLO) accu-racy [4–8]. In equilibrium, there have been attempts toextract transport coefficients also using nonperturbativelattice QCD methods [9–11].

Heavy quarks are unique probes of the transport prop-erties of the quark gluon plasma (QGP) because of theirlarge mass compared to the other scales of the medium.Pair production and annihilation processes are negligi-ble, and all the heavy quarks within the medium are cre-ated in the hard processes preceding the formation of theQGP. Heavy quark observables carry information aboutthe entire history of the medium.

In conventional transport approaches to heavy-ion col-lisions, the effects of early-time, nonequilibrium evolu-tion are usually ignored. Only very recently studies haveaddressed the importance of the nonequilibrium evolu-tion. For heavy quark diffusion specifically, a Fokker-Planck approach to the evolution of heavy quarks in anon-equilibrium gluon plasma or “glasma” present in theearly stages of the evolution was used in [12, 13]. Theauthors find that the glasma phase can have a sizablecontribution to momentum broadening and energy loss ofheavy quarks. At later stages of the non-equilibrium evo-lution when the quasiparticle description is valid, recentstudies have indicated that the pre-equilibrium effectscan be important [14, 15]. In [16] jet momentum broad-ening in the glasma was investigated. The main result isthat a colored particle can accumulate sizable momentum

broadening during the glasma phase (〈p2⊥〉 = 1−4GeV2).

One might thus expect the pre-equilibrium phase to beimportant also for heavy quarks.

The heavy quark momentum diffusion coefficient κ canbe studied in multiple ways. In thermal equilibrium, ithas been calculated with perturbative methods [1, 2, 17–20] and studied with a standard lattice approach [21–26]. Another possibility is to use lattice gauge theoryin the classical approximation. This technique has beenapplied to the heavy quark diffusion coefficient κ∞ andthe jet quenching coefficient q in thermal equilibrium sys-tems [27–29]. However, one of the benefits of the classicalapproach is that one can also study nonperturbative sys-tems out of equilibrium, as we will do here. Once theheavy quark diffusion coefficient is known, one can use itto understand heavy quark flow and spectra by incorpo-rating the diffusion process in a simulation of the heavyion collision [18, 30–32].

The heavy quark diffusion coefficient κ is not only im-portant for momentum broadening of heavy quarks, butit also has applications for quarkonia. Quarkonia can bemodelled using an open quantum system approach [33–37], and their time-evolution is governed by the Lind-blad equation [38, 39]. The equation of motion needstwo transport coefficients as an input, one of which isthe heavy-quark diffusion coefficient.

Our aim in this paper is to understand momentumbroadening 〈p2〉 and the evolution of the momentumdiffusion coefficient κ of heavy quarks in a far-from-equilibrium overoccupied system, with the main motiva-tion coming from initial stages in ultrarelativistic heavyion collisions. After the collision, occupation numbersof gluonic fields at the characteristic momentum scaleQ are non-perturbatively large ∼ 1/g2 [40, 41] duringinitial stages in a weak-coupling thermalization picture.In this case, classical-statistical simulations are applica-ble and have been widely used [42–64] to understand thepre-equilibrium dynamics in the collision.

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Merger of Dark Matter Axion Clumpsand Resonant Photon Emission

Mark P. Hertzberg,a Yao Li,b and Enrico D. Schiappacassec,d

a Institute of Cosmology, Dept. of Physics and Astronomy, Tufts University, Medford 02155MA, USAb School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, ChinacDepartment of Physics, P.O. Box 35 (YFL), FI-40014 University of Jyvaskyla, FinlanddHelsinki Institute of Physics, P.O. Box 64, FIN-00014 University of Helsinki, Finland

E-mail: mark.hertzberg@tufts.edu, neolee@sjtu.edu.cn,enrico.e.schiappacasse@jyu.fi

Abstract. A portion of light scalar dark matter, especially axions, may organize intogravitationally bound clumps (stars) and be present in large number in the galaxy today. Itis therefore of utmost interest to determine if there are novel observational signatures of thisscenario. Work has shown that for moderately large axion-photon couplings, such clumps canundergo parametric resonance into photons, for clumps above a critical mass M?

c determinedprecisely by some of us in Ref. [1]. In order to obtain a clump above the critical mass in thegalaxy today would require mergers. In this work we perform full 3-dimensional simulationsof pairs of axion clumps and determine the conditions under which mergers take place throughthe emission of scalar waves, including analyzing head-on and non-head-on collisions, phasedependence, and relative velocities. Consistent with other work in the literature, we findthat the final mass from the merger M?

final ≈ 0.7(M?1 +M?

2 ) is larger than each of the originalclump masses (for M?

1 ∼ M?2 ). Hence, it is possible for sub-critical mass clumps to merge

and become super-critical and therefore undergo parametric resonance into photons. We findthat mergers are expected to be kinematically allowed in the galaxy today for high Peccei-Quinn scales, which is strongly suggested by unification ideas, although the collision rate issmall. While mergers can happen for axions with lower Peccei-Quinn scales due to statisticalfluctuations in relative velocities, as they have a high collision rate. We estimate the collisionand merger rates within the Milky Way galaxy today. We find that a merger leads to a fluxof energy on earth that can be appreciable and we mention observational search strategies.

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Dark Higgs Dark Matter

Cristina Mondino,1 Maxim Pospelov,2 Joshua T. Ruderman,1 and Oren Slone3

1Center for Cosmology and Particle Physics, Department of Physics,New York University, New York, NY 10003, USA

2William I. Fine Theoretical Physics Institute, School of Physics and Astronomy,University of Minnesota, Minneapolis, MN 55455, USA

3Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544, USA(Dated: May 7, 2020)

A new U(1) “dark” gauge group coupled to the Standard Model (SM) via the kinetic mixingportal provides a natural dark matter candidate in the form of the Higgs field, hd, responsible forgenerating the mass of the dark photon, γd. We show that the condition mhd ≤ mγd , togetherwith smallness of the kinetic mixing parameter, ε, and/or dark gauge coupling, gd, leads the darkHiggs to be sufficiently metastable to constitute dark matter. We analyze the Universe’s thermalhistory and show that both freeze-in, SM→ {γd, hd}, and freeze-out, {γd, hd} → SM, processes canlead to viable dark Higgs dark matter with a sub-GeV mass and a kinetic mixing parameter in therange 10−13 . ε . 10−6. Observable signals in astrophysics and cosmology include modifications toprimordial elemental abundances, altered energetics of supernovae explosions, dark Higgs decays inthe late Universe, and dark matter self-interactions.

Introduction. Evidence for dark matter constitutes oneof the strongest arguments for extending the StandardModel (SM) with Dark Sector(s) (DS). One of the sim-plest examples is an additional U(1)d gauge symmetryassociated with its gauge boson, the dark photon γd, thatmediates DS-SM interactions. It is commonly assumedthat Dark Matter (DM) is charged under U(1)d and isrepresented by additional states in the DS.

A great deal of theoretical and experimental attentionhas been devoted to the study of such a DS [1, 2] in recog-nition of the fact that its mass scale can be at, or below1 GeV, offering a variety of new probes. In this study, weshow that an even more minimal option exists: the fieldresponsible for generating the mass of γd, a dark Higgshd, is a viable DM candidate with different phenomeno-logical implications than those commonly assumed [1, 2].Throughout the paper, we analyze the salient features ofDark Higgs Dark Matter (DHDM), including its (meta)-stability and genesis through cosmic history.

For such a model, the relevant DS Lagrangian is

LDS = |Dµφ|2 − 1

4(Fµνd )2 − ε

2Fµνd Fµν − V (φ) , (1)

where φ is a charged scalar field, Fµν and Fµνd are theSM and dark photon field strengths, and ε is the ki-netic mixing parameter. The scalar potential, V (φ) =−µ2|φ|2 + λ|φ|4, generates a non-zero Vacuum Expecta-tion Value (VEV) for φ, 〈φ〉 = µ/

√2λ ≡ v/

√2, that

spontaneously breaks the U(1)d gauge symmetry. Ex-panding φ around the VEV, φ = (v + hd)/

√2, gives the

mass terms for the dark Higgs, mhd =√

2λv, and forthe dark photon, mγd = gdv, where gd is the dark gaugecoupling, and one can define αd ≡ g2

d/4π.

For a natural choice of couplings, λ ∼ g2d, the dark

particle’s masses are expected to be of similar order,mhd ∼ mγd . In particular, it is possible for hd to have

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FIG. 1. Decay processes of dark sector particles. Left andcentral diagrams are dark Higgs decay channels available for4me < mhd < 2mµ and mhd < mγd . The right diagram isthe dark photon decay channel for 2me < mγd < 2mµ.

a mass below, or close to that of γd, with a potentiallylong lifetime [3, 4].

When mhd < mγd , the only open decay channels foran MeV-scale dark Higgs are hd → e+e−e+e−, and theloop-induced process, hd → e+e−. The associated Feyn-man diagrams are depicted in Fig. 1 and require doubleinsertions of ε, leading to a dark Higgs lifetime that scalesas τhd ∝ ε−4 (for full expressions of the decay widths seee.g. Ref. [3]). An additional Higgs portal coupling couldlead to SM-DS Higgs mixing and further decay channelsfor hd. However, if such a coupling is absent at treelevel, it only appears at one loop, and the resulting SM-DS Higgs mixing parameter θh−hd ∝ (εgd)

2(v/vEW) isnegligibly small.

Combining the decay channels for 4me � mhd < 2mµ,the approximate decay width for DHDM is

τUΓ2e,4e ' 8× 10−8[ ε

10−9

]4 [ αd10−4

] [ mhd

100 MeV

]f.(2)

Here, τU is the age of the Universe, and f = f(mhd/mγd)is a dimensionless function of order unity at mhd = mγd .Note that τUΓ2e,4e < 1 is an insufficient condition for hdto be DM, since stronger bounds are imposed by limitson diffuse photon spectra [5] and precision measurementsof CMB anisotropies [6, 7].

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NuclearPhysics A

www.elsevier.com/locate/procedia

XXVIIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions(Quark Matter 2019)

One fluid might not rule them all

You Zhoua, Wenbin Zhaob,c, Koichi Muraseb,c, Huichao Songb,c,d

aNiels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen, DenmarkbDepartment of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China

cCollaborative Innovation Center of Quantum Matter, Beijing 100871, ChinadCollaborative Innovation Center of Quantum Matter, Beijing 100871, China

Abstract

In this proceeding, we present our recent investigations on hydrodynamic collectivity in high-multiplicity proton–protoncollisions at

√s = 13 TeV using the iEBE-VISHNU hybrid model with different initial condition models, called HIJING,

super-MC and TRENTo. We find that with carefully tuned parameters, hydrodynamic simulations can give reasonabledescriptions of the measured two-particle correlations. However, multi-particle single and mixed harmonics cumulantscan not be described by hydrodynamics with these three initial conditions, even for the signs in a few cases. Furtherstudies show that the non-linear response plays an important role in the hydrodynamic expansion of the p–p systems.Such an effect can change c2{4} from a negative value in the initial state to a positive value in the final state. The failureof the hydrodynamic description of multi-particle cumulant triggers the questions on whether the hydrodynamics canrule all collision systems, including p–p collisions at the LHC.

Keywords: hydrodynamics, flow, proton–proton collisions

1. Introduction

Ultra-relativistic heavy-ion collisions at the LHC provide a unique opportunity to study the Quark–Gluon Plasma (QGP). With the new developments on both flow measurements and model calculations, theunderstanding of the properties of the QGP and its fluctuating initial conditions have been improved to anunprecedented level. In addition to the detailed study of flow in Pb–Pb and Xe–Xe collisions, the flowphenomena in small collision systems like p–Pb and p–p collisions, which initially expected to serve as areference data, have been studied in great detail [1, 2, 3]. Surprising observation of flow phenomena in thesesmaller collision systems has attracted a lot of attention. It challenges both the hydrodynamic model as the“standard model” in heavy-ion physics and the PYTHIA model as the “standard tool” for the minimum-biasp–p physics at the same time. While it has been commonly accepted that the observed large anisotropicflow is attributed to the creation of the QGP in heavy-ion collisions, the origin of the similar size of flow

Email addresses: you.zhou@cern.ch (You Zhou), Huichaosong@pku.edu.cn (Huichao Song)

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Comprehensive measurements of cross sections andspin observables of the three-body break-up channel indeuteron-deuteron scattering at 65 MeV/nucleon

R. Ramazani-Sharifabadi1,2, H.R. Amir-Ahmadi1, M.T. Bayat1, A. Deltuva3, M. Eslami-Kalantari4, N. Kalantar-Nayestanaki1, St. Kistryn5, A. Kozela6, M. Mahjour-Shafiei2, H. Mardanpour1, J.G. Messchendorp1,M. Mohammadi-Dadkan1,7, A. Ramazani-Moghaddam-Arani8, E. Stephan9, and H. Tavakoli-Zaniani1,4

1 KVI-CART, University of Groningen, Groningen, The Netherlands2 Department of Physics, University of Tehran, Tehran, Iran3 Institute of Theoretical Physics and Astronomy, Vilnius University, Vilnius, Lithuania4 Department of Physics, School of Science, Yazd University, Yazd, Iran5 Institute of Physics, Jagiellonian University, Krakow, Poland6 Institute of Nuclear Physics, PAS, Krakow, Poland7 Department of Physics, University of Sistan and Baluchestan, Zahedan, Iran8 Department of Physics, Faculty of Science, University of Kashan, Kashan, Iran9 Institute of Physics, University of Silesia, Chorzow, Poland

Received: date / Revised version: date

Abstract. Detailed measurements of five-fold differential cross sections and a rich set of vector andtensor analyzing powers of the 2H(d, dp)n break-up process using polarized deuteron-beam energy of65 MeV/nucleon with a liquid-deuterium target are presented. The experiment was conducted at theAGOR facility at KVI using the BINA 4π-detection system. We discuss the analysis procedure includinga thorough study of the systematic uncertainties. The results can be used to examine upcoming state-of-the-art calculations in the four-nucleon scattering domain, and will, thereby, provide further insightsinto the dynamics of three- and four-nucleon forces in few-nucleon systems. The results of coplanar con-figurations are compared with the results of recent theoretical calculations based on the Single-ScatteringApproximation (SSA). Through these comparisons, the validity of SSA approximation is investigated inthe Quasi-Free (QF) region.

Key words. deuteron-deuteron scattering – three-body break-up – single-scattering approximation –quasi-free region – vector and tensor analyzing powers – nuclear forces

PACS. XX.XX.XX No PACS code given

1 Introduction

Understanding the degrees of freedom involved in thenuclear forces is of paramount importance in subatomicphysics. According to the standard model of particlephysics, the nuclear force is considered to be the resid-ual of strong interactions between quarks and gluons. Itis common to interpret the interactions between nucle-ons by meson-exchange theory which was introduced byYukawa in 1935. This theory successfully described the in-teraction between two nucleons with the exchange of vir-tual mesons between them [1]. The discovery of the pionand subsequently heavier mesons stimulated researchersto develop boson-exchange models to describe nucleon-nucleon interactions. To date, several phenomenologicalnucleon-nucleon (NN) potentials have been derived based

on Yukawa’s model [2]. Some of them are successfullylinked to the underlying fundamental theory of the quan-tum chromodynamics (QCD) by chiral perturbation the-ory, χPT [2,3].

Applying high-precision NN potentials to describe sys-tems composed of at least three nucleons shows strik-ing discrepancies between theoretical calculations and fewparticular experimental observables, despite its major suc-cesses. For instance, rigorous Faddeev calculations basedon these NN potentials for the binding energy of tri-ton, which is the simplest three-nucleon system, under-estimate the experimental data [4] by 10%. In addition,they show large discrepancies with cross section data inelastic nucleon-deuteron scattering [5]. These observationsshow that calculations based on NN potentials are not suf-ficient to describe systems that involve more than two nu-