Physics with CBM Claudia Höhne, GSI Darmstadt CBM collaboration Outline motivation, physics case observables.

Physics with CBM

Claudia Höhne, GSI Darmstadt

CBM collaboration

Outline

• motivation, physics case

• observables

2 Claudia Höhne China, November 2006

Mapping the QCD phase diagramWhat do we know from theory? → Predictions from lattice QCD:

• crossover transition from partonic to hadronic matter at small B and high T, Tc(B=0) = 151 – 192 MeV • critical endpoint in intermediate range of the phase diagram (current estimates B = 300 – 700 MeV, T ≈ 140 – 160 MeV) • first order deconfinement phase transition at high B but moderate T

What do we know from experiment? → Heavy-ion collisions:

• chemical freeze-out curve from final hadron yields measured in the experiments: T ≈ 160 MeV at top RHIC energy • top SPS, RHIC (high T, low B): indications for relevance of partonic degrees of freedom• lower SPS, AGS (intermediate T-B range): intriguing observations around 30 AGeV beam energy

[Andronic et al. Nucl. Phys. A 772, 167 (2006).

→ CBM@FAIR !

3 Claudia Höhne China, November 2006

Mapping the QCD phase diagram (II)

→ CBM@FAIR – high B, moderate T:

searching for the landmarks of the QCD phase diagram

• first order deconfinement phase transition • chiral phase transition• QCD critical endpoint

in A+A collisions from 10-45 AGeV starting in 2015

[Andronic et al. Nucl. Phys. A 772, 167 (2006).

4 Claudia Höhne China, November 2006

Dense baryonic matter

• baryon density in central cell (Au+Au, b=0 fm) in transport calculations HSD (mean field, hadrons + resonances + strings), QGSM similar results

• enormous energy and baryon densities reached! ( > crit)

[CBM physics group, C. Fuchs, E. Bratkovskaya priv. com.]

5 Claudia Höhne China, November 2006

Phase diagram

[Bratkovskaya et al., PRC 69 (2004) 054907]

• UrQMD calculation of T, B as function of reaction time

(open symbols – nonequilibrium,

full symbols – appr. pressure equilibrium)

• phase border crossed already at rather low energies

(see also results from 3-fluid hydrodynamics)

• critical point in reach?

CBM energy range: 15 - 35 AGeV for Au+Au

6 Claudia Höhne China, November 2006

High baryon density matter!

[Rapp, Wambach, Adv. Nucl. Phys. 25 (2000) 1, hep-ph/9909229]

[Mishra et al ., PRC 69, 015202 (2004) ]

• hadronic properties should be effected by the enormous baryon densities which will be created

• (partial) restoration of chiral symmetry?

D

7 Claudia Höhne China, November 2006

ObservablesGoal of CBM experiment: comprehensive and systematic (energy, system size) studies of all relevant diagnostic probes including:

• hadrons, event-by-event fluctuations, correlations, collective flow

• multistrange hyperons

• low-mass vector mesons

• open charm (D0, D±, c)

• charmonium (J/, ')

10-1 100 101 102 103 10410-6

10-4

10-2

100

102

104

AGS SPS RHIC HSD ' 99

__

D(c)

J/D(c)

KK+

+

Mul

tipl

icit

yAu+Au (central)

Energy [A GeV]

[W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 753]

rare probes!

CBM energy range

8 Claudia Höhne China, November 2006

Observables (II)

physics topics

deconfinement at high B ?

softening of EOS ?

order of phase transition ?

Critical point ?

in-medium properties of hadrons

onset of chiral symmetry restoration at high B

observables

strangeness production: K,

charm production: J/, D

flow excitation function

event-by-event fluctuations

e+e-

open charm

CBM: rare probes → high interaction rates!

9 Claudia Höhne China, November 2006

Strangeness productiondeconfinement

[NA49, C.Blume et al., nucl-ex/0409008]

• s-production mechanism different in hadronic / partonic scenario

• maximum of strangeness production at 30 AGeV

→ change from hadronic to partonic phase?

• CBM energy range: 15 – 35/45 AGeV (depending on A)

• verify and extend energy dependence!

10 Claudia Höhne China, November 2006

J/ suppression

• screening of cc pairs in partonic phase

• anomalous J/ suppression observed at top-SPS and RHIC energies

• signal of deconfinement?

• energy dependence?!

[E. Scomparin for NA 60, QM05]

deconfinement

11 Claudia Höhne China, November 2006

collective flow

• collapse elliptic flow of protons at lower energies signal for first order phase transition?! [e.g. Stoecker, NPA 750 (2005) 121, E. Shuryak, hep-ph/0504048]

• full energy dependence needed!central

midcentral

peripheral

[NA49, PRC68, 034903 (2003)]

deconfinement

12 Claudia Höhne China, November 2006

K/ fluctuationsCritical point

• dynamical fluctuations of the K/ ratio increase towards lower energies

• not reproduced by UrQMD: resonance contribution?

energy dependence needed for lower energies!

[C.Roland et al., nucl-ex/0403035

S. Das, SQM06]

22mixeddatadyn

13 Claudia Höhne China, November 2006

modifications → l+l- In medium

within acceptance

• enhancement of low-mass dilepton pairs seen at low (2 AGeV, C+C) and high (158 AGeB, In+In) energies! → broadening of the – meson

• intermediate energies with highest baryon densities?

[R. Holzmann for HADES, QM05][E. Scomparin for NA 60, QM05]

14 Claudia Höhne China, November 2006

D-mesons[W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745]

SIS18 SIS100/ 300

D-mesons sensitive to medium!

In medium[M

ishra et al .,

PR

C 69, 0152

02 (200

4) ]

15 Claudia Höhne China, November 2006

D-mesons (II)

[E. Bratkovskaya, W. Cassing, private communication]

In medium

• Dropping D-meson masses with increasing light quark density

might give a large enhancement of the open charm yield at 25 A GeV !

16 Claudia Höhne China, November 2006

CBM – summary • CBM offers a very interesting physics program exploring the QCD phase-diagram at highest baryon densities but still moderate temperatures

• unique features expected in CBM energy range: first order phase transition, critical point

• CBM as 2nd generation experiment will be able to study rare probes, fluctuations and correlations!

• exciting physics from ~2015 on!

17 Claudia Höhne China, November 2006

CBM collaboration

Russia:IHEP ProtvinoINR TroitzkITEP MoscowKRI, St. Petersburg

China:CCNU WuhanUSTC Hefei

Croatia: RBI, Zagreb

Portugal: LIP Coimbra

Romania: NIPNE Bucharest

Poland:Krakow Univ.Warsaw Univ.Silesia Univ. KatowiceNucl. Phys. Inst. Krakow

LIT, JINR DubnaMEPHI MoscowObninsk State Univ.PNPI GatchinaSINP, Moscow State Univ. St. Petersburg Polytec. U.

Ukraine: Shevchenko Univ. , Kiev

Cyprus: Nikosia Univ.

Univ. Mannheim Univ. MünsterFZ RossendorfGSI Darmstadt

Czech Republic:CAS, RezTechn. Univ. Prague

France: IPHC Strasbourg

Germany: Univ. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. FrankfurtUniv. Kaiserslautern

Hungaria:KFKI BudapestEötvös Univ. Budapest

India:VECC KolkataSAHA KolkataIOP BhubaneswarUniv. ChandigarhUniv. VaranasiIlT Kharagpur

Korea:Korea Univ. SeoulPusan National Univ.

Norway:Univ. Bergen

Kurchatov Inst. MoscowLHE, JINR DubnaLPP, JINR Dubna

46 institutions

> 400 members

Strasbourg, September 2006