1. The Physics of Compressed Nuclear Matter at GSI and FAIR Mazurian Lakes Conference on Physics 2009 Joachim Stroth, Goethe-University / GSI, Germany

2. Agenda o Motivation o Recent remarkable results from SIS18 o The persepective and challenge at FAIR o Summary

3. The phase diagram of nuclear matter Chemical freeze-out points derived from Statistical Hadronization Model  Universal conditions for freeze-out (?)  Limiting temperature T max ?  Why is it woking at low beam energies? QCD inspired models demonstrate the melting of the condesates. A. Andronic, P. Braun-Munzinger, K. Redlich, J. Stachel J. Cleymans, K. Redlich LQCD explores unknown regions from solid grounds at  B =0.  T c = T max ?  1st order phase transition  Critical point ? Schäfer, Wambach priv. communication Schäfer, Wambach priv. communication Leupold J.Phys.G32:2199,2006 LHC RHIC SPS FAIR SIS AGS QGP Hadron gas F. Karsch et al., Z. Fodor et al.

4. Ignorant interpretation (Cloudy Bag Model) q q q q q q q q q q q q q q q q q q q q q q q q

5. T  T c, m B ~ 0 q q q q q q q q q q q q q q q q q q q q q q q q qq - - - - - - - - - Excitation/melting of the vacuum/cloud.  smooth cross over

6. T << T c, finite  B q q q q q q q q q q q q q q q q q q q q q q q q qq -

7. T << T c, finite  B q q q q q q q q q q q q q q q q q q q q q q q q Bag fusion  mixed phase

8. Phase diagram from large N c limit McLerran, Pisarski: QM09  conjecture for N c = 3 Quarkyonic Matter: Confined gas of perturbative quarks!

9. Strange Particle Production at SIS18 HADES, Ar+KCl at 1.76 GeV/u FOPI (P. Gasik CPOD 2009), Al+Al at 2 GeV/u T chem = 70  3 MeV  B = 746  15 MeV R C = 2.6  0.4 fm preliminary Statistical Model: THERMUS, S. Wheaton and J. Cleymans, hep-ph/0407174 Transport: UrQMD, M. Bleicher, S. Vogel at al. HADES collab.: arXiv:0907.3582 HADES collab.: arXiv:0907.3582 and arXiv:0902.3487arXiv:0902.3487

10. Properties of the Fireball below E beam < 30 GeV/u Long lifetime of the high- density phase Baryon dominated Extented region of a strongly interacting hadron gas Red line from Hadron Gas Model, Sasaki QM09

11. Dileptons from 1 and 2 GeV/u 12 C+ 12 C runs Phys.Rev. Lett 98(2007) 052302 Phys. Lett. B 663 (2008) 43  Good normalization established in  0 region  Measured pair excess in C+C scales with beam energy as   production  What is the contribution from the initial phase? l+l+ l-l- ** ** l+l+ l-l- ** l+l+ l-l-

12. The solution to the DLS puzzle C+C collisions compared to NN reference HADES data agrees with DLS

13. Electron pairs from Ar+KCl at 1.76 GeV/u First observation of  mesons in HI collisions at these energies x 2 PLUTO A Compared to reference after subtraction of contributions from  preliminary F ~ 3

14. The Future at GSI and FAIR SIS18 Several FOPI runs on strangeness production in 2008 – 2010 Upgraded 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 reactions SIS300: Full exploitation of rare probes a high  B; fluctuations, flow

15. Particle multiplicities in detection channel Au+Au at 25 GeV/u HSD transport calculation and statistical hadronization model. Not fully dressed in HI collisions at AGS and lower SPS energies

16. The Quest for the Highest Densities J. Randrup and J. Cleymans, hep-ph/0607065 Freeze-out configurations for X+X collisions in the net-baryon density and energy density plane.

17. Low-mass vector mesons: what do they tell about chiral symmtery restoration?

18. Low-mass lepton pairs, … the link to the microscopic properties of dense baryonic matter … the link to the microscopic properties of dense baryonic matter. Special role of the  meson: – short life time – „photon-like“ – coupling to baryons! isentropic expansion Thermal dilepton rates see e.g. R. Rapp, J. Wambach and H. Hees : arXiv:0901.3289, and S. Leupold, U. Mosel and V. Metag arXiv:0907.2388 R.Arnaldi,etal.[NA60collaboration], Phys.Rev.Lett.96,162302(2006 R.Arnaldi,etal.[NA60collaboration], Phys.Rev.Lett.96,162302(2006 )

19. New approaches in theory Hybrid codes for modeling the reaction dynamics 1.Non-equilibrium initial conditions via UrQMD 2.Hydrodynamic evolution or transport calculation 3.Freeze-out via hadronic cascade (UrQMD) hydro running time hydro start time Pb+Pb, central (Petersen et al., PRC 78:044901, 2008, arXiv: 0806.1695) Introduce virtual photon emissivity from in-medium spectral functions into hydro codes R. Rapp, H. van Hees, V. Toneev, J. Wambach, B. Friman, Texas A&M, TU Darmstadt, GSI, Giessen, Frankfurt

20. Ring Imaging Cherenkov Detector Transition Radiation Detectors Electron identification in CBM

21. Electron-pair reconstruction in CBM Challenge -No electron identification before tracking -Background due to material budget of the STS -Sufficient  discrimination (600   /event  misidentification 10 -4 )  Reduction of background by reconstructing pairs from  -conversion and   Dalitz decay via their track topology. e-e- e+e+  00   00  Track Segment Track Fragment

22. Background rejection performance Central Au+Au collisions at 25 GeV/u Free cocktail only (without medium contribution) Statistic: 200000 events = beam spill on target All e + e - Combinatorial bg Invariant mass spectrum after all cuts applied Invariant mass spectrum identified e + e -

23. M ll > 200 MeV/c 2 safety factor ;) NA60 In+In @ 158 AGeV CERES Pb+Au @ 40 AGeV CERES Pb+Au @ 158 AGeV (σ/σ tot = 28%) CERES Pb+Au @ 158 AGeV (σ/σ tot = 7%) CERES Pb+Au @ 158 AGeV PHENIX Au+Au @ √s = 200 AGeV Comparison of expected performance to existing dilepton experiments

24. Charmonium suppression. c c -

25. The Charm of CBM Rare but measurement feasible! – Very sparse experimental information – At threshold, production mechanism in pA and AA unclear. Open charm in CBM BRM / 10 12 events 1) 4 10 -5 56000 1 10 -4 174000 9 10 -5 195000 4 10 -5 103000 10 12 events  40 weeks running at 10 5 interaction rate.  Event selection: Real-time vertex finding in 20 Gbyte data/s. W. Cassing, E.L. Bratkovskaya, and A. Sibirtsev, Nucl.Phys.A691,753(2001)

26. Charm propagation How are the produced charm quarks propagating in the dense phase, quark like or (pre-)hadron like ? – Charmonium over open charm as indicator! – Charmed baryons important for a complete picture. – Are there indications of collectivity. O. Linnyk, E. Bratkovskaya and W. Cassing, arXiv:0808.1504v1 A. Andronic, P. Braun-Munzinger, et al., Phys. Lett. B 659 (2007) 149, arXiv:0708.1488

27. 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.