Physics with CBM Claudia Höhne, GSI Darmstadt CBM collaboration Outline • motivation, physics case • observables
Jan 21, 2016
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