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Physics with CBM

Physics with CBM. Claudia Höhne, GSI Darmstadt CBM collaboration. Outline motivation, physics case observables. Mapping the QCD phase diagram. What do we know from theory? → Predictions from lattice QCD: crossover transition from partonic to hadronic matter at small m B and high T,

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Physics with CBM

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

  2. Mapping the QCD phase diagram • What do we know from theory? → Predictions from lattice QCD: • crossover transition from partonic to hadronic matter at small mB and high T, • Tc(mB=0) = 151 – 192 MeV • critical endpoint in intermediate range of the phase diagram • (current estimates mB = 300 – 700 MeV, T ≈ 140 – 160 MeV) • first order deconfinement phase transition at high mB 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 mB): indications for relevance of partonic degrees of freedom • lower SPS, AGS (intermediate T-mB range): intriguing observations around 30 AGeV beam energy → CBM@FAIR ! [Andronic et al. Nucl. Phys. A 772, 167 (2006).

  3. Mapping the QCD phase diagram (II) • → CBM@FAIR – high mB, 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. 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! (e > ecrit) [CBM physics group, C. Fuchs, E. Bratkovskaya priv. com.]

  5. Phase diagram • UrQMD calculation of T, mB 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 [Bratkovskaya et al., PRC 69 (2004) 054907]

  6. High baryon density matter! • hadronic properties should be effected by the enormous baryon densities which will be created • (partial) restoration of chiral symmetry? [Rapp, Wambach, Adv. Nucl. Phys. 25 (2000) 1, hep-ph/9909229] [Mishra et al ., PRC 69, 015202 (2004) ] r D

  7. Observables • Goal 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±, Lc) • charmonium (J/y, y') rare probes! CBM energy range [W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 753] CBM energy range

  8. Observables (II) physics topics observables deconfinement at high rB ? softening of EOS ? order of phase transition ? strangeness production: K, L, S, X, W charm production: J/y, D flow excitation function in-medium properties of hadrons  onset of chiral symmetry restoration at high rB r, w, f e+e- open charm Critical point ? event-by-event fluctuations CBM: rare probes → high interaction rates!

  9. deconfinement Strangeness production [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. J/y suppression • deconfinement [E. Scomparin for NA 60, QM05] • screening of cc pairs in partonic phase • anomalous J/y suppression observed at top-SPS and RHIC energies • signal of deconfinement? • energy dependence?!

  11. collective flow central midcentral peripheral • deconfinement • 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! [NA49, PRC68, 034903 (2003)]

  12. Critical point K/p fluctuations [C.Roland et al., nucl-ex/0403035 S. Das, SQM06] • dynamical fluctuations of the K/p ratio increase towards lower energies • not reproduced by UrQMD: resonance contribution? •  energy dependence needed for lower energies!

  13. In medium modifications    → l+l- 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 r – meson • intermediate energies with highest baryon densities? [E. Scomparin for NA 60, QM05] [R. Holzmann for HADES, QM05]

  14. D-mesons • In medium [W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745] D-mesons sensitive to medium! SIS100/ 300 SIS18 [Mishra et al ., PRC 69, 015202 (2004) ]

  15. D-mesons (II) • 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 ! [E. Bratkovskaya, W. Cassing, private communication]

  16. 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. CBM collaboration China: CCNU Wuhan USTC Hefei Croatia: RBI, Zagreb Univ. Mannheim Univ. Münster FZ Rossendorf GSI Darmstadt Norway: Univ. Bergen Kurchatov Inst. Moscow LHE, JINR Dubna LPP, JINR Dubna Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Nucl. Phys. Inst. Krakow LIT, JINR Dubna MEPHI Moscow Obninsk State Univ. PNPI Gatchina SINP, Moscow State Univ. St. Petersburg Polytec. U. Hungaria: KFKI Budapest Eötvös Univ. Budapest Cyprus: Nikosia Univ. India: VECC Kolkata SAHA Kolkata IOP Bhubaneswar Univ. Chandigarh Czech Republic: CAS, Rez Techn. Univ. Prague France: IPHC Strasbourg Portugal: LIP Coimbra Romania: NIPNE Bucharest Ukraine: Shevchenko Univ. , Kiev Univ. Varanasi IlT Kharagpur Korea: Korea Univ. Seoul Pusan National Univ. Russia: IHEP Protvino INR Troitzk ITEP Moscow KRI, St. Petersburg Germany: Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Frankfurt Univ. Kaiserslautern 46 institutions > 400 members Strasbourg, September 2006

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