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Chemical fit at RHIC

Workshop on Thermalization and Chemical Equilibration in Heavy Ions Collisions at RHIC (July 20-21, 2001 at BNL). Chemical fit at RHIC. Masashi Kaneta LBNL. Many thanks to V.Koch, H.G.Ritter, N.Xu (LBNL), Z.Xu (BNL), and Organizers. Outlook. Introduction Model Data

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Chemical fit at RHIC

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  1. Workshop on Thermalization and Chemical Equilibration in Heavy Ions Collisions at RHIC (July20-21, 2001 at BNL) Chemical fitat RHIC Masashi Kaneta LBNL Masashi Kaneta, LBNL

  2. Many thanks to V.Koch, H.G.Ritter, N.Xu (LBNL), Z.Xu (BNL), and Organizers Masashi Kaneta, LBNL

  3. Outlook • Introduction • Model • Data • Freeze-out parameters • Model uncertainties • Summary • Open issues Masashi Kaneta, LBNL

  4. Introduction • Bulk properties of the heavy ion collisions • Statistical approach for particle production • Dynamical information – may be lost? • Chemical freeze-out • occurs at an uniform condition? <E>/<N> ~ 1GeV • SIS (<1GeV), AGS (~5 GeV), SPS (~20 GeV), and RHIC (130 GeV) The study for RHIC data P. Braun-Munzinger,D.Magestro, K. Redlich, and J. Stachel, hep-ph/0105229 W. Florkwski, W. Broniowski, and M. Michalec, nucl-th/0106009 F. Becattini, workshop in Trento, June, 2001. N. Xu and M. Kaneta, nucl-exp/0104021 Masashi Kaneta, LBNL

  5. Model Refs. J.Rafelski PLB(1991)333 J.Sollfrank et al. PRC59(1999)1637 Hadron resonance ideal gas Particle density of each particle Qi : 1 for u and d, -1 for u and d si : 1 for s, -1 for s gi:spin-isospin freedom mi : particle mass Tch : Chemical freeze-out temperature mq : light-quark chemical potential ms : strangeness chemical potential gs : strangeness saturation factor All resonances and unstable particles are decayed Comparable particle ratios to experimental data Masashi Kaneta, LBNL

  6. Model (cont.) • Hadron resonance ideal gas • including higher mass resonances(1.7GeV) • For mid-rapidity, no requirement of • Strangeness neutrality • Charge/Isospin conservation , ,, ,’, , f0(980) , a0 (980), h1(1170), b1 (1235), a1 (1260), f2(1270), f1 (1285), (1295), (1300), a2(1320), f0(1370), (1440), (1420), f1 (1420), (1450), f0 (1500), f1 (1510), f2’(1525), (1600), 2(1670), (1680), 3(1690), fJ(1710), (1700) p, n, N(1440), N(1520), N(1535), N(1650), N(1675), N(1680), N(1700) (1232), (1600), (1620), (1700) K, K*, K1(1270), K1(1400), K*(1410), K0*(1430), K2*(1430), K*(1680) , (1450), (1520), (1600), (1670), (1690) , (1385), (1660), (1670) , (1530), (1690)  Masashi Kaneta, LBNL

  7. Ratio data Red : the values from slide of QM2001 Black : PRL (including submitted) Blue: the values from figure in proceedings of QM2001 Masashi Kaneta, LBNL

  8. Freeze-out parameters 450 340 21 19 0.32 0.25 69 52 Note: The errors are estimated as 2min+1 The feed-down factor of 0.5 is assumed. Masashi Kaneta, LBNL

  9. Ratios, experiment vs. model Central Peripheral Masashi Kaneta, LBNL

  10. Strange baryon ratios Central see also J. Zimanyi et al, hep-ph/0103156 (quark coalescence) Masashi Kaneta, LBNL

  11. Systematics Lattice QCD predictions Central collisions This analysis P.Braun-Munzinger et al. W. Florkowski et al. Temperature increases with beam energy and being close to phase boundary Neutron star parton-hadron phase boundary <E>/<N>~1GeV, J.Cleymans and K.Redlich, PRC60 (1999) 054908 Masashi Kaneta, LBNL

  12. Model uncertainties } weak • Mass cut-off • Boltzmann vs. Boson/Fermion • Weak decay feed-down • Depend on particle species (i.e. c ) • No equal opportunity to decayed particles • deferent pT kick • Depend on detector • Test of the effect in case of • fraction of accepted weak decay (fW) =0, 0.5, 1.0 Masashi Kaneta, LBNL

  13. Feed-down effects B [MeV] Tch [MeV] Central collisions, top15% Peripheral collisions, >50% s s [MeV] fraction of accepted weak decay Masashi Kaneta, LBNL

  14. Summary • Only mid-rapidity ratios used; • With selected fW the Tch and  are consistent with what expected; • Centrality dependence; • Systematic uncertainty needed to be evaluated; Masashi Kaneta, LBNL

  15. Open issues • Particle ratios are described by statistical model well • Dynamical information? • Global vs. local equilibration • Connection between Tch and Lattice QCD Tc? Masashi Kaneta, LBNL

  16. Test: rapidity dependence Au + Au at 200 GeV (b3 fm) (a) Temperature: Increasing as the rapidity width y open up; (b) Baryon chemical potential: increase with y; (c) Strange chemical potential: decrease with y; (d) Strange saturation factor: decrease with y; Thermal parameters depend on the kinetic cuts! RQMD(v2.4) NEXUS(V1.1) J. Phys. G: Nucl. Part. Phys. 27 (2001) 589, M. Kaneta and N. Xu Masashi Kaneta, LBNL

  17. Open issues • F. Karsch, hep-lat/0106019 • Not fully ideal system at 4TC • Collective effects ? • ??? Masashi Kaneta, LBNL

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