Latest results of nucleon spin structure measurements from PHENIX

RIKEN/RBRCItaru Nakagawa

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The Relativistic Heavy Ion Collideraccelerator complex

at Brookhaven National Laboratory

PHENIXSTAR

Brahmspp2pp

2

RHIC p+p accelerator complex

3

v vv

BRAHMS & PP2PP

STARPHENIX

AGS

LINACBOOSTER

Pol. Proton Source

Spin Rotators

20% Snake

Siberian Snakes

200 MeV polarimeter Rf Dipoles

RHIC pC “CNI” polarimeters

PHOBOS

RHIC

absolute pHpolarimeter

SiberianSnakes

AGS pC “CNI” polarimeter

5% Snake

Coulomb-Nuclear Interference

PHENIX Experiment

4Pioneering High Energy Nuclear Interaction EXperiment

13 Countries; 70 Institutions

Abilene Christian University, Abilene, TX 79699, U.S.Baruch College, CUNY, New York City, NY 10010-5518, U.S.Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.University of California - Riverside, Riverside, CA 92521, U.S.University of Colorado, Boulder, CO 80309, U.S.Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.Florida Institute of Technology, Melbourne, FL 32901, U.S.Florida State University, Tallahassee, FL 32306, U.S.Georgia State University, Atlanta, GA 30303, U.S.University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.Iowa State University, Ames, IA 50011, U.S.Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.University of Maryland, College Park, MD 20742, U.S.Department of Physics, University of Massachusetts, Amherst, MA 01003-9337, U.S. Morgan State University, Baltimore, MD 21251, U.S.Muhlenberg College, Allentown, PA 18104-5586, U.S.University of New Mexico, Albuquerque, NM 87131, U.S. New Mexico State University, Las Cruces, NM 88003, U.S.Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.Department of Physics and Astronomy, Ohio University, Athens, OH 45701, U.S.RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.Chemistry Department, Stony Brook University,SUNY, Stony Brook, NY 11794-3400, U.S.Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.University of Tennessee, Knoxville, TN 37996, U.S.Vanderbilt University, Nashville, TN 37235, U.S.

Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, BrazilInstitute of Physics, Academia Sinica, Taipei 11529, TaiwanChina Institute of Atomic Energy (CIAE), Beijing, People's Republic of ChinaPeking University, Beijing, People's Republic of ChinaCharles University, Ovocnytrh 5, Praha 1, 116 36, Prague, Czech RepublicCzech Technical University, Zikova 4, 166 36 Prague 6, Czech RepublicInstitute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech RepublicHelsinki Institute of Physics and University of Jyväskylä, P.O.Box 35, FI-40014 Jyväskylä, FinlandDapnia, CEA Saclay, F-91191, Gif-sur-Yvette, FranceLaboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, FranceLaboratoire de Physique Corpusculaire (LPC), Université Blaise Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere Cedex, FranceIPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, FranceDebrecen University, H-4010 Debrecen, Egyetem tér 1, HungaryELTE, Eötvös Loránd University, H - 1117 Budapest, Pázmány P. s. 1/A, HungaryKFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences (MTA KFKI RMKI), H-1525 Budapest 114, POBox 49, Budapest, HungaryDepartment of Physics, Banaras Hindu University, Varanasi 221005, IndiaBhabha Atomic Research Centre, Bombay 400 085, IndiaWeizmann Institute, Rehovot 76100, IsraelCenter for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, JapanHiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, JapanKEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, JapanKyoto University, Kyoto 606-8502, JapanNagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki 851-0193, JapanRIKEN, The Institute of Physical and Chemical Research, Wako, Saitama 351-0198, JapanPhysics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, JapanDepartment of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, JapanInstitute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, JapanChonbuk National University, Jeonju, KoreaEwha Womans University, Seoul 120-750, KoreaHanyang University, Seoul 133-792, KoreaKAERI, Cyclotron Application Laboratory, Seoul, South KoreaKorea University, Seoul, 136-701, KoreaMyongji University, Yongin, Kyonggido 449-728, KoreaDepartment of Physocs and Astronomy, Seoul National University, Seoul, South KoreaYonsei University, IPAP, Seoul 120-749, KoreaIHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, RussiaINR_RAS, Institute for Nuclear Research of the Russian Academy of Sciences, prospekt 60-letiya Oktyabrya 7a, Moscow 117312, RussiaJoint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RussiaRussian Research Center "Kurchatov Institute", Moscow, RussiaPNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, RussiaSaint Petersburg State Polytechnic University, St. Petersburg, RussiaSkobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Vorob'evy Gory, Moscow 119992, Russia Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden

Feb 2011

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PHENIX detector

• Global detectors– beam-beam counter (BBC),

zero-degree calorimeter (ZDC)• Minimum-bias trigger• Luminosity measurement• Local polarimeter

• Philosophy– high resolution at the cost of

acceptance– high rate capable DAQ– excellent trigger capability for

rare events• Central Arms

– |h| < 0.35, Df = /p 2×2– Momentum and energy

measurement, particle-ID– Detecting electron, photon,

hadron– Small amount of material to

reduce conversion background

• Muon Arms– 1.2 < |h| < 2.4– Momentum measurement and

muon-ID– Hadron absorber (muon piston)

DG DOUBLE HELICITY ALL RESULTS

7

Probe Advantage

p0 Statistics

h Different fragmentation

p0 - p0 correlation Kinematic constraint

charged p DG sign

heavy flavor decay e- Lower x, g-g dominant

MPC cluster Lower x

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PDFs from Asymmetries

• Example:o Choose channel with high statistics: p + p → π0 + Xo Complicated mixture of amplitudes, changes

as a function of kinematics.

o How does one extract ΔG from the experimentally determined:

o Requires calculational techniques based on factorization.

gqgq G

G

q

q

qqqqq

q

q

q

gggg G

G

G

G

1LL

B Y

N N R N NA

P P N N R N N

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Factorization

,

ˆ a bf f fX hLL a b f

a b

f f D

f h z

Δfa,b = polarized quark and gluon distribution functions

Δ

Δ

Δ Dhf = fragmentation

function for

Partonic cross section from pQCD

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Polarized gluon distribution (I) • Central Rapidity

p0

Phys. Rev. D83,032001 (2011)

Abundant Statistics

Sensitive to sign of gp0 , p+/-

h Different fragmentation

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Polarized gluon distribution (II) • Central + Forward Rapidity, Low Energy

Phys. Rev. D87, 012011 (2013)

Single e High purity of glue-glue subprocess

Forward Cluster Small x ~ 10-3 0 at s = 62.4 GeV

Phys. Rev. D79, 012003 (2009)

High x

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Extraction of Gluon Polarization

Quark

Strangeness

Gluon

Anti-quark

QCD Global

Fit

DISSIDIS

pp

PHENIXSTAR(2005,2006)

HERMESCOMPASSJlab…

RHIC data constrain ongluon polarization!

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QCD global analysis Interpretation

DSSV++ (with latest results)

First Positive Polarization DG Result :

SEA QUARK POLARIZATIONPRELIMINARY AL

W FROM RUN12

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Probe Rapidity Advantage

W->e central Good S/N

W->m forward Enhanced sea quark

W-Boson Production @ √s = 500 GeV

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Parity Violation AsymmetryClean flavor separationw/o fragmentation uncertainty

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Single e,m PT Spectra

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W->e+ (Mid Rapidity)

W+BG

BG only

W->m+ (Forward Rapidity)

Signal

Background PT [GeV/c]

S/B ~ 1/3

Background estimation in data driven manner

Resolution Improvement for better S/N in progress

W-boson Asymmetry (Run12)

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Poor knowledge of Sea quark Polarization

Wide rapidity coverage

• Boxes are systematic uncertainties from background

• Run 2012 Beam Polarization uncertainty P/P = 3.4% (not shown)

W measurement Run13 Projections

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Existing data + Run13 Data

Delivered Luminosity

RHIC white paper

Existing data

TRANSVERSE SINGLE SPIN ASYMMETRY AN

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Probe Rapidity Advantage

p0, eta central Good S/N

MPC Cluster forward Enhanced sea quark

neutron Very Forward

Transverse structure of the nucleon

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• Single transverse-spin asymmetry

– Expected to be small in hard scattering at high energies

• FNAL-E704– Unexpected large asymmetry found

in the forward-rapidity region– Development of many models

based on perturbative QCD

RightLeft

RightLeftN dd

ddA

p

p

Transverse-spin physics• For establishment of TMD and higher-

twist approach– Single transverse-spin asymmetry (SSA)

of inclusive hadrons– Sivers effect

• Sivers distribution function (initial state)– transverse-momentum dependence of

partons inside the transversely-polarized nucleon

– Collins effect• Transversity distribution (initial state)

– correlation between transversely-polarized nucleon and transversely-polarized partons inside

• Collins fragmentation function (final state)

– Higher-twist effect• quark-gluon & multi-gluon correlation 22

S

P

kT

,pp

p

S

Pp

p

S

q

kT

,π

Sivers effect

Collins effect

Inclusive 0

Transverse-spin physics

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Forward EM cluster at s = 200 GeV

no decrese at high pT expected from higher-twist effect

constrains gluon Sivers effect

arXiv:1312.1995 To be published from PRD

Midrapidity 0 and

neutron

neutronBBC hits

Very Forward Neutron

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large negative asymmetryused for local polarimetry!

Phys. Rev. D88, 032006 (2013)

Single pion exchange?

3-dimensional nucleon structure• Nucleon structure beyond the simple parton picture• Many-body correlation of partons

– To describe the orbital motion inside the nucleon

• Parton distribution in transverse direction– Extended/generalized picture of the parton distribution– Transverse-momentum dependence (TMD)– Space distribution (tomography)

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Phenomenological modelwith GPD data

Lattice QCD calculation

MPC-EX upgrade

• MPC (Muon Piston Calorimeter) – Electromagnetic calorimeter

• MPC-EX– Preshower detector– Commissioning in 2014– Experiment in 2015-2016

• 3.1 < || < 3.8– Installed in the muon piston

• Direct photon asymmetry– To distinguish the Sivers effect and

the higher-twist effect• Collins asymmetry in jets

– 0 correlation with jet-like clusters26

MPC

MPC-EX

49pb-1, P=0.6

Twist-3 p+p prediction

SIDIS (TMD) p+p prediction

Phys Rev. D 83 094001 (2011)arXiv 1208.1962v1 (2012)

AN

xF

Charged clusters with >=3 tracks, single-track p0’s

sPHENIX upgrade• sPHENIX– Barrel upgrade– Forward upgrade– Partial installation and commissioning in

2018-2019– Completion and experiment in 2021-

2022• Barrel upgrade baseline

– Compact jet detector– Using upgraded RHIC accelerator– For precision measurement of jet, dijet,

photon-jet correlation to understand the nature of QGP

• Barrel upgrade extension– Additional tracking layers– Preshower detector– For heavy-flavor and internal jet

structure measurements27

sPHENIX forward upgrade• Open geometry

– Wide kinematic coverage of photon, jet, leptons and identified hadrons

• Compatible design for eRHIC detector (ePHENIX)– Constraint from IR design of eRHIC (|z| < 4.5m)– Hermeticity for exclusive measurements

28GEMStation4

EMCal

HCal

GEMStation2

z (cm)

R (cm)

HCal

η~1

η~4

η~-1

R (cm)

SiliconStation1

MuID

Central silicon tracking

EMCal& Preshower RICH

GEMStation3

Aerogel

twist 3

Fit of SIDIS

SIDIS olds = 200 GeVy=3.3 jets

sPHENIX forward upgrade• Sivers effect in Drell-Yan process

– Valence quark region at x0.2 with 1 < < 4 coverage

• Jet asymmetry– Sivers effect or higher-twist effect

• Asymmetry inside of jets– Collins effect

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jet ® h+X

Summary• Origin of the nucleon spin 1/2

– Gluon-spin contribution AL• First non-zero positive gluon polarization by pQCD fit on Run9 data

– Sea-quark contribution• Wide rapidity coverage. Sensitive to sea quark polarization at

forward

• Understanding of transverse-spin phenomena– Sivers effect / Collins effect / higher-twist effect– 3-dimensional nucleon structure– Many-body correlation of partons

• AN measurements

• The forward sPHENIX upgrades toward understanding of the 3-dimensional nucleon structure– Polarized Drell-Yan measurement / jet asymmetry and

asymmetry inside of jets– Evolution to ePHENIX toward electron-proton collisions at

eRHIC 30

BACKUP

31

Run11 Central Arm W->e

32Backgrounds could be mitigated by relative isolation cut

Run9 PRL106,062001 (2011)

Signal electron :• High momentum electron• Isolated

Single Electron PT Spectra

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Back

grou

nd D

omin

ant

Sign

al +

Bac

kgro

und

Signal

Background

• Power Law Counting

Background Shape Fixed in

10<PT<20 GeV/c

• Jacobian Peak (PYTHIA+GEANT)

+ Power Low Background Fitting• Resulting Background

contamination 14 ~ 17%.

Run11

Forward W-> m Analysis

34

Single Muon PT Spectra

35

Efficiency corrections W/Z cross section employed

RHICBOS NLO S/B estimation from fixed W/Z

cross section (RHICBOS NLO)

S/B ~ 1/3

Background estimation in data driven manner

Resolution Improvement for better S/N

The First Forward ALW

Results

36

More to come!

Run11 Run12Luminosity 25 50

First Forward W Asymmetry Results!

References

37

[1]

Global Fit including Run9 0 ALL 38

By S.Taneja et al (DIS2011)ala DSSV with slightly different uncertainty evaluation approach

DSSV DSSV + PHENIX Run9 0 ALL

No node …Uncertainties decreasedA node at x~0.1 ?

Charged pion Cross Section

39

Charge separated fragmentation functions are not well constrained in DSS FFs

In good agreement with STAR

40

HBD Analysis for Heavy Flavor Decay e-

41

HBD Signal Occupancy

42

DG Extraction from ALLHFe

43

Open charm production dominates in pT range of 0.50 < pT < 1.25 GeV/c (J/ψ <2%, b quark<5%)

pQCD prediction for ALLopen charm

obtained from CTEQ6M PDFs + PYTHYA + LO hard scattering cross section

ALLopen charm ~|∆g/g(x, µ)|2

|∆g(x, µ)| = C g(x, µ) is assumed

Results: |∆g/g( logx ,µ)|⟨ ⟩ 2 <3.3 ×10 −2 (1σ)

and 10.9 ×10 −2 (3σ)

Central W Analysis

44

Central Arm AL

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The PHENIX Detector• Philosophy

– high resolution & high-rate at the cost of acceptance

– trigger for rare events

• Central Arms– |h| < 0.35, Df ~ p– Momentum, Energy, PID

• Muon Arms– 1.2 < |h| < 2.4– Momentum (MuTr)

• Muon Piston Calorimeter– 3.1 < |h| < 3.9

46

h+

,0

m

MPC

Further Sea Quark Measurement w/ DY

47

FVTX (S) FVTX (N)

VTX

VTX

ϒ-states

J/Ψ

Drell Yan

charmbeauty

Invariant mass (GeV)

S/B contributionsw/o vertex detector

Low

-mass

DY

High-mass DY

Extract DY events from heavy flavorsusing FVTX