2008/9/1J-PARC J-PARC でありうる将来 としての重イオン物理 小沢 恭一郎（東大・理） (Thanks for a talk by A. JPS02)

2008/9/1J-PARC J-PARC as a Dense QCD Lab ρ０ρ０ ρBρB ~200MeV T QGP Neutron Star RHIC J-PARC

2008/9/1J-PARC Explore QCD phase diagram By A. Ohnishi High density In addition, hadron properties can be measured in several QCD media.

2008/9/1J-PARC RHIC での成功要因 クォーク・グルーオン・プラズマの生成 衝突の初期状態の摂動論的な計算による決定 –Clear なプローブの設定 流体力学を用いた時間発展の解析 4 系の温度・密度状態の時間発展の定量的評価が重要

2008/9/1J-PARC AGS data の理解 Freeze out and hadron cross sections are well understood.

2008/9/1J-PARC Access to high density  Lepton & Photon  Rare Events / fluctuations Formed medium has a trajectory on a QCD phase. High Intensity is essential

2008/9/1J-PARC Hopeful measurements p T spectra of all particles –Extend to higher p T region –Now, we know hard probes have rich physics. Lepton & photon –Direct access to high dense matter –Mass modification of hadrons –Thermal emission Event fluctuation and rare events –High intensity beam is required Collective flows (related to EOS) –Detailed study of p T and particle dependence Several difference QCD media are generated using different energy and collision species. In addition, improved model calculations can be expected.

2008/9/1J-PARC Interesting features Strangeness J-PARC energy

2008/9/1J-PARC Charm production W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 74

2008/9/1J-PARC Collective flow Direct Flow (dP x /dy) Direct flow ~ 0 Smaller spectator-participant interaction

2008/9/1J-PARC Flow (II) Radial Flow Pressure history Large Radial flow  Large baryon density

2008/9/1J-PARC Quark condensates 2008/3/6 K. Ozawa  Spontaneous breaking of a symmetry is marked by: * a non-zero order parameter, the quark condensate in the case of QCD: heavy ion reactions: A+A  V+X m V (  >>  0 ;T>>0) SPS LHC RHIC elementary reaction: , p,   V+X m V (  =  0 ;T=0) , . p - beams J-PARC LEPS2 At Nuclear Density High T High  J-PARC Heavy-Ion G.E.Brown and M. Rho, PRL 66 (1991) 2720 T.Hatsuda and S. Lee, PRC 46 (1992) R34 メソン質量に対する予測

2008/9/1J-PARC PREDICTED “ SPECTRA ” Situation is not so simple, several theories and models predict spectral function of vector mesons (  ). –Lowering of in-medium mass –Broadening of resonance  - meson  - meson 13 R. Rapp (Nucl. Phys A661(1999) 238c 高温・高密度に対する計算の例 原子核密度に対する計算の例 F. Klingl et al. NPA 624 (1997) 527 NPA 650 (1999) 299

2008/9/1J-PARC PREDICTED “ SPECTRA ” (CONT ’ D) 14 structure in spectral function due to coupling to baryon resonances M. Lutz et al., Nucl. Phys. A 706 (2002) 431  structure due to coupling to S11,P13 resonances  P. Muehlich et al., Nucl. Phys. A 780 (2006) 187 原子核中のバリオンとの結合を考慮に入れた例

2008/9/1J-PARC KEK E325,   e + e - with p+A Cu  <1.25 (Slow) Invariant mass spectrum for slow  mesons of Cu target shows a excess at low mass side of . Induce 12 GeV protons to Carbon and Cupper target, generate vector mesons, and detect e+e- decays with large acceptance spectrometer. Let ’ s go to J-PARC! 100 times larger statistics Mass Shift: m  = m 0 (1 -   /  0 ) for  = 0.03

2008/9/1J-PARC J-PARC can accelerate Heavy ions? According to Mori-san ’ s presentation at NP02 –Main ring is OK –Booster is questionable –Alternative idea is using FFAG. Sorry, I forgot to update the information. – I expect inputs from other people.

2008/9/1J-PARC FAIR 2007 start of project 2012 first experiment 2015 completion Their R&D for detectors and accelerators are well performed. BUT, we have an accelerator!!

2008/9/1J-PARC Summary Heavy ion collisions at J-PARC can explore QCD phase diagram. Several interesting measurements are remaining, even after AGS. –Equation of state at high density matter –Critical end point –Hadron mass and chiral symmetry Why don ’ t we accelerate heavy ions at J-PARC?

2008/9/1J-PARC Back ups

2008/9/1J-PARC Taken from T. Hatsuda ’ s slide

2008/9/1J-PARC Taken from T. Hatsuda ’ s slide

2008/9/1J-PARC