The physics of dense baryonic matter:

From HADES to CBM

DM2010International Workshop on High Density MatterSTIAS, Stellenbosch, South Africa

Joachim Stroth, Goethe-University Frankfurt / GSI

Agenda

o Introductiono Dileptons from light collision systemso Vector meson productiono Strangeness productiono The future at SIS18, SIS100 and SIS300o Summary

The HADES experiment @ GSI

The HADES Mission

Phase 1 (2002 - 2008) -> Upgrade– Light collision systems (limited granularity of TOF system)

Phase 2 (2010 – 2015) – Heavy collision systems, -induced reactions

Phase 3 (FAIR/SIS100)– Excitation function up to 10 GeV/u (medium-heavy systems)

Search (in this region) for• medium-effects• partial restoration of chiral

symmetry • onset of decofinement

Beam energies of 1-2 GeV/u

p - beams

SIS 18

SIS 200T [MeV] 300

LHC

RHIC

SPS

Partial restoration of chiral symmetry

From vector manifestation of hidden local symmetry:

“... to suggest that the dileptons measured in relativistic heavy-ion collisions do not provide direct information on the spontaneous breaking of chiral symmetry and hence on the mechanism for mass generation of light-quark hadrons.”

Brown, Harada et al. Prog.Theor.Phys.121:1209-1236,2009

W. Weise et al.+ BR scaling (PRL 1991)

R. Pisarski, L. McLerran et al.

HADES run statistics (phase 1)

p+Nb

Ar+KCl 1.67GeV/u

pp 3.5

C+C 2 GeV/udp 1.25 GeV/u

pp 1.25 GeV/uC+C 1 GeV/u

o 6 runs between 2002 and 2008o 1010 events taken o 100 days beam on target

After upgrade in 2010:100-200 TByte in 30 days

FW > 7o

Eur.Phys.J.A41:243-277,2009

Dileptons from light collision systems

Electron pairs from C+C collisions at 1 and 2 GeV/u

Phys.

Rev. Le

tt 9

8(2

007)

05

2302

Phys.

Lett

. B

663 (

200

8)

43

Good normalization established in 0 region. Evidence for yield above contributions from

decays of long-lived hadrons. What are the sources of contributions from

the early phase?

e+

e-

*

*

e+

e-

*

e+e -

The solution to the DLS puzzle?

• HADES data in the acceptance of DLS, compared to DLS data.

0.0 0.2 0.4 0.6 0.810-8

10-7

10-6

10-5

10-4

10-3

10-2

0.0 0.2 0.4 0.6 0.810-8

10-7

10-6

10-5

10-4

10-3

10-2

HADES

HSD: Dalitz Dalitz Dalitz Dalitz Brems. NN Brems. N All

C+C, 1.0 A GeVno medium effects

1/N

dN/d

M [

1/G

eV /c

2 ]

HSD: Dalitz Dalitz Dalitz Dalitz Brems. NN Brems. N All

M [GeV/c2]

HADES

C+C, 1.0 A GeVin-medium effects: CB+DM

1/N

dN/d

M [

1/G

eV /c

2 ]

E. Bratkovskaya et al., PLB 2008. Modified description of Bremsstrahlung in HSD inspired by Kaptari et al.

Dileptons from pp and np reactions at 1.25 GeV/u compared to HSD

Data from HADES pp and dp (tagged n) at 1.25 GeV/uCocktail from HSD calculation 2008 with revised description of Bremsstrahlung

Data: HADES collaboration, arXiv:0910.5875 [nucl-ex]

Electron pairs from C+C collisions compared to NN reference

HADES collaboration, arXiv:0910.5875 [nucl-ex]

N

N

N

N

N*, ΔN

N

N

N

N*, ΔN

N

N

N

Dileptons from Ar+KCl at 1.76 GeV/u

Electron pairs from Ar+KCl collisions at 1.76 GeV/u

First observation ofmesons in HI collisions at these (SIS) energies

HADES collaboration, Nucl.Phys.A830:483C-486C,2009

Fit: exponential + gaussian

30-40 counts In peak!

Excess radiation in Ar+KCl at 1.67 GeV/u

Compared to reference after subtraction of contributions from Indication for radiation from

the medium.

Multistep processes or multi-particle correlation.

RR

N

N

N

N

N

N

R

e-

e+

N

N

Excess yield scales stronger than linear with Apart

Data for 0 and from TAPS collaboration

Dilepton excess scales with beam energy like production

C+C (DLS)C+C (HADES)Ca+Ca (DLS)Ar+KCl (HADES)

Systematic of the excess yield

Refined HSD vacuum calculation

o Enhanced bremsstrahlung from elastic NN collisions according to “Kaptari-Kämpfer” (OBE) prescription.

o Reduced vector-meson production via the LUND string in order to better match pp exp. Data.

o Improved isospin dependence of the channels NN-> V+NN and +N-> V+N.

HSD, November 2009 release

“It’s a bingo”

17

Dileptons from pp at 3.5 GeV

HSD, Nov. 09 release K. Schmidt, et al. Phys. Rev. C 79, 064908 (2009)

Normalized to π peak

Dilepton production in pp at 3.5 GeV

Particle productionLUND string fragmentation

Particle productionthrough baryonic resonances

Slope parameters in mass bins

Mee = 0.35 – 0.50 0.50 – 0.65 >0.65 GeV

Strong increase of slope parameter with increasing pair mass.No explanation yet.

strangeness

Strangeness production in 1.75 GeV/u Ar+KCl reactions

Λ

0s

-

High-statistics measurement of and

but also:0

s →

→ p -

→

-→ -

HADES collaboration:Phys.Rev.Lett.103:132301,2009Eur.Phys.J.A40:45-59,2009Phys.Rev.C80:025209,2009

HADES data and the SHM

Particle multiplicities largely in accordance with SHM o yield explained (non-strange particle )o− underestimated by SM

■ Ar+KCl at 1.76 GeV/u THERMUS fitS.Wheaton and J.Cleymans,J.Phys.G31(2005)S1069

T= 73T= 736 6 bb=770=77043 43 (MeV)(MeV)

RC =2.4 0.8 fmRfireball =4.9 1.4 fm 2=2.1 (no - )

J.Cleymans priv. communication

/-ratio

M (→ K+K-) : (2.6 ± 0.7) ·10-4

M (→ e+e-) : (6.7 ± 2.7) ·10-3

In accordance with SHM.

No OZI suppression in the production.

038.0013.0/ 043.0R

Multi-strange baryons

€

MΞ − ≈ 0.1 × Mss

2

Probability (Mss) to produce in Ar+KCl collisions a strange quark pair is ≈ 5 × 10-2.

qqq q

qq qqq

q qqqqqqqqqq

q

qqq

Bag fusion quarkyonic matter?

Strange quarks “trapped” in bubbles?

The HADES upgrade …

… from 8 /day (Ar+KCl) to 170 /day (Ag+Ag) and dilepton statistics like NA60

The RPC time-of-flight system

Full-system test results: • t 78 ps• x 8 mm• ~ 97%

D. Belver et al . NIM A602(2008) 687, 788E. Blanco et al. NIM A602(2008) 691

RPC

D. Belver et al . NIM A602(2008) 687, 788E. Blanco et al. NIM A602(2008) 691

Leading institute:Coimbra, Portugal

CTS

VME CPUMU

...

RPC

F. Wall

MDC

RICH

Shower

VULOM3

Start, Veto

TOF

Ethernet

HADES DAQ System Overview

To the F

ront End E

lectronics

Fröhlich et al., IEEE Trans. Nucl.Sci. Vol. 55, Issue 1 (2008) 59

Average data rate 150 Mbyte/s. Trigger rate up to 20 KHz.

Current proposalCurrent proposal

2010-2012 (2-3 campaigns). Main emphasis on:

Dielectron & strangeness production in heavy systems

• low mass (0.15<Me+e- <0.5) excess studies

• vector meson spectroscopy

• /K production: differential distributions,

y, pt (increased acceptance due to RPC !) , flow

• - production characteristics

Two HI collision systems : medium size ,eg. Ag+Ag, and Au+Au at maximal beam

energies of 1.65, 1.25 AGeV, respectively.

The Future at FAIR

SIS18Upgraded HADES (20 kHz reaction rate) Au+Au and Ag+Ag, pion induced reactions from 2010 on.SIS100:Joint running of HADES and preCBM,multistrange particle and lepton pair excitation function,charm production in proton induced reactionsSIS300:Full exploitation of rare probes a high B;

fluctuations, flow

Mission:Systematics and sensitivity!Phase boundary and critical point.

Towards FAIR

The Quest for the highest densities

J. Randrup and J. Cleymans, hep-ph/0607065

Freeze-out configurations for HI collisions!

Density in the centre of the collision zone

UrQMD

The CBM detector

o More than one million reactions / second (no trigger)o Fast high resolution tracking in a compact dipole field directly after the targeto High speed DAQ and triggero Excellent particle identificationo Flexible arrangement of PID detectors and calorimeters:

Dilepton production

Thermal dilepton rate ...

oVT ,, 00

isentropic expansion

...or from transport

3 4

0

( ), ( ), ( ),..B coll

t t

d N dT x x v x dx

dMdydp dp

In future: combine the best of the two worlds!

Charm production

o How are the produced charm quarks propagating in the dense phase, quark-like or (pre-) hadron-like?

◊ Hidden over open charm as indicator (J/ψ, ψ', D0, D)◊ Charmed baryons important for a complete picture (c, Ξc)

◊ Are there indicators of collectivity

[HSD: O. Linnyk et al., Int.J.Mod.Phys.E17, 1367 (2008)] [SHM: A. Andronic et al., Phys. Lett. B 659 (2008) 149]

Charm detection in CBMo Challenge:

◊ Find displaced decay vertex in an environment of hundreds of charged tracks

◊ Event selection:real-time vertex finding in 20Gbyte/s

o Needs vertex detector with:◊ High resolution◊ Minimal material budget◊ Radiation tolerance

o Monolithic Active Pixel Sensors, also foreseen in ILC, STAR

c = 312 m

35

Diamond 300 µm

~ 60 µm Si

< 200 µm Si

~ 60 µm Si

< 320 µm SiFactor 4-5 thinner than conventional solution

IMEC, Strasbourg, Frankfurt

Summary

– „Long-lived“ states of dense nuclear matter are produced in collisions of heavy ion at energies of a few GeV/u.

– The phase in the high-density region might be much more exotic then a hadron/resonance gas.

– Unfortunately, there is no smoking gun, but:• Fast equillibration• „Sub-threshold“ production• Strong broadening of in-medium states

– Close collaboration with, and novel approaches in theory are necessary to make the case.

The HADES collaboration LIP-Laboratório de Instrumentação e Física Experimental de Partículas , 3004-516 Coimbra, Portugal Smoluchowski Institute of Physics, Jagiellonian University of Cracow, 30-059 Kraków, Poland GSI Helmholtzzentrum für Schwerionenforschunm, 64291 Darmstadt, Germany Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, 01314 Dresden, Germany Joint Institute of Nuclear Research, 141980 Dubna, Russia Institut für Kernphysik, Johann Wolfgang Goethe-Universität, 60438 Frankfurt, Germany II.Physikalisches Institut, Justus Liebig Universität Giessen, 35392 Giessen, Germany Institute for Nuclear Research, Russian Academy of Science, 117312 Moscow, Russia Physik Department E12 & Excellence Cluster Universe, TUM, 85748 München, Germany Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus Institut de Physique Nucléaire (UMR 8608), CNRS/IN2P3 - Université Paris Sud, F-91406 Orsay Cedex, France Nuclear Physics Institute, Academy of Sciences of Czech Republic, 25068 Rez, Czech Republic Departamento de Física de Partículas, University of Santiago de Compostela, 15782 Santiago de C.a, Spain

The CBM collaborationChina:Tsinghua Univ., BeijingUSTC, HefeiCCNU, WuhanCroatia: University of SplitRBI, Zagreb Czech Republic:Techn. Univ., PragueCAS, RezFrance:IPHC StrasbourgGermany: GSI, DarmstadtFZ Dresden-RossendorfUniv. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. Heidelberg, ZITI

Univ. of Kashmir, SrinagarBanaras Hindu Univ., VaranasiKorea:Korea Univ. SeoulPusan National Univ.Norway:University of BergenPoland:Silesia Univ. KatowiceAGH Univ. KrakowJagiellonian Univ., KrakowWarsaw Univ.Portugal: LIP CoimbraRomania: NIPNE, BucharestBucharest University

Univ. Frankfurt, IKFUniv. Frankfurt, Inst.Comp.Sc.Univ. MünsterUniv. WuppertalHungaria:KFKI, BudapestEötvös Univ. BudapestIndia:Aligarh Muslim Univ., AligarhIOP, BhubaneswarPanjab Univ., ChandigarhGauhati Univ., GuwahatiUniv. of Rajasthan, JaipurUniv. of Jammu, JammuIIT, KharagpurSAHA, KolkataUniv. of Calcutta, KolkataVECC, Kolkata

Russia:VBLHE, JINR, DubnaLIT, JINR, DubnaLPP, JINR, DubnaPNPI, GatchinaITEP, MoscowMEPhI, MoscowKurchatov Inst. MoscowSINP, Moscow State Univ. Obninsk State Univ.IHEP, ProtvinoKRI, St. PetersburgSt. Petersburg Polytec. U.INR TroitzkUkraine: INR, KievShevchenko Univ. , Kiev

Split, 2009 56 institutions> 400 members

Thank you

Exclusive electron pair production inpp collisions at 1.25 GeV

Three particle missing mass (MX)

pppe+e-X

200 eventsfor Me+e- > 140 MeV/c2

pp p+ppe+e-

HADES data

Mee>140 MeV/c2

Prelim

inary

MX(GeV/c2)Mee(GeV/c2)

Electron pair invariant missing mass (Mee)

HSD in-medium calculations

Phi to omega ratio

... vector manifestation of hidden local symmetry ... to suggest that the dileptons measured in relativistic heavy-ion collisions do not provide direct information on the spontaneous breaking of chiral symmetry and hence on the mechanism for mass generation of light-quark hadrons.

XXI HADES Coll. Meet. March 2010 43

Systematics of slopes at 1.76 GeV/u

Why are slopes of ρ/ω and so different ?

π0 and η from TAPS

HADES has a two level trigger system

• LVL1 trigger Multiplicity34% more central events of events

• LVL2 trigger

at least one electron candidate

GEANT simulation with UrQMD events

2.1× 109 triggered LVL1 events in the Ar+KCl run!

Trigger

Effenberger, Giessen

Dileptons from pp and np reactions at 1.25 GeV/u

PLUTO: resonance: production: fixed to 0 by N() = 3/2 N(0), decay: Krivoruchenko et al.,

EM form-factor: QED, Krivoruchenko, GM=3, GE=GC=0 or VMD-like, Wan & Iachello, int. J. Mod. Phys. A20(2005) 1846 meson: constrained by CELSIUS/WASA data, H. Calén et al. PRC 58, 1998 NN Bremsstrahlung: is currently implemented a-lá Kaptari and assuming isotropic emission

p+p data: results from OBE (coherent sum of and NN terms) seems to be too high (already cross section is too high (factor 2-4), NN Bremsstrahlung also?)

n+p data: not explained by theory, clear contribution of additional sources

HADES collaboration, arXiv:0910.5875 [nucl-ex]