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Bulk Properties and Collective Phenomena in High-Energy Collisions

Explore dn/dy spectra, chemical and thermal freeze-out processes, radial flow, recombination, jet suppression, and jet-quark interactions in heavy-ion collisions. Investigate global polarization, rapidity dependence, eccentricity, and baryon transport at RHIC and LHC experiments.

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Bulk Properties and Collective Phenomena in High-Energy Collisions

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  1. Rapporteur 3 Bulk Properties and Collective Phenomena ShinIchi Esumi Univ. of Tsukuba ShinIchi Esumi, Univ. of Tsukuba

  2. dn/dy, spectra, chemical/thermal freeze-out stopping, radial flow, recombination HBT, global polarization rapidity dependence eccentricity definition event by event v2 fluctuation v1 and v2 scaling jet and its correlation with v2 charm quark interaction and collectivity direct photon as a probe of bulk matter ShinIchi Esumi, Univ. of Tsukuba

  3. baryon transport (stopping) AGS NA49 preliminary SPS RHIC 62 ‘net’ proton dN/dy (BRAHMS preliminary) RHIC 200 LHC 5500 ShinIchi Esumi, Univ. of Tsukuba

  4. STAR (sNN=130 GeV) Inverse slope parameter [GeV/c2] mass [GeV/c2] hadron spectra after strong radial expansion STAR Preliminary STAR Preliminary ShinIchi Esumi, Univ. of Tsukuba

  5. Kp thermal fit STAR Preliminary Min-Bias 10% central 5% central hadron production at chemical freeze-out close to the phase boundary BRAHMS BRAHMS ShinIchi Esumi, Univ. of Tsukuba

  6. p/- baryon transport + radial flow + recombination + jet suppression p/+ Au+Au 200GeV STAR preliminary ShinIchi Esumi, Univ. of Tsukuba

  7. Rinv (fm) STAR preliminary mT (GeV/c) HBT freeze-out is given by energy density. strong effect from collective expansion and space-time correlation. reconstruct source image without assuming the source shape ShinIchi Esumi, Univ. of Tsukuba

  8. global polarization Lambda polarization w.r.t. (normal to) directed event plane no significant signal observed, upper limit : |PL,L|~10-2 ShinIchi Esumi, Univ. of Tsukuba

  9. rapidity dependence of identified particle nuclear suppression y=0 y=1 y=3.1 pions kaons protons No strong indication of rapidity dependence ShinIchi Esumi, Univ. of Tsukuba

  10. rapidity dependence of identified particle v2 =0 ≈3 BRAHMS preliminary  K p No strong indication of rapidity dependence, the strong rapidity dependence on the integrated v2 is more or less explained by the mean pT. Meson/baryon splitting might be different between y=0 and y=3, if statistical significance is improved. ShinIchi Esumi, Univ. of Tsukuba

  11. eccentricity definition Standard Eccentricity Participant Eccentricity 200 GeV 200 GeV Cu+Cu Cu+Cu Au+Au Au+Au arXiv:nucl-ex/0610037, submitted to PRL ShinIchi Esumi, Univ. of Tsukuba

  12. v2 scales with <epart> and energy densidy ShinIchi Esumi, Univ. of Tsukuba

  13. event by event v2 fluctuation vs epart fluctuation PHOBOS epartprediction This relative v2 fluctuation can be explained by initial epart fluctuation… MC with nofluctuations ShinIchi Esumi, Univ. of Tsukuba

  14. eccentricity re-visited v2 = ? participant e modified participant e e (1) exclude one participant to define a new frame (2) calculate position of the excluded participant in the new frame (3) repeat above 2 steps for all participants (4) get eccentricity using positions of all participants Each participant position is defined in its own frame. If particles are generated from position of participants, it is more natural to get eccentricity in this way. I would not say this is the best, just like to say there is still a room for improvements. All participant positions are used to define a new axis and to get eccentricity simultaneously in the new rotated axis. We try to remove a particle from reaction plane definition to avoid auto-correlation between particle and event plane, when measuring v2 of the particle. eSTD ePART eMOD e e Au+Au Cu+Cu y (fm) Participant Modified Standard x (fm) e impact parameter : b (fm) impact parameter : b (fm) ShinIchi Esumi, Univ. of Tsukuba

  15. centrality dependence of v2 comparison of v2 ratio : Cu+Cu/Au+Au (>1) at central (<10%) collisions between experiments STAR PHENIX PRELIMINARY epart 0-5% 1.5/0.9 = 1.7 5-10% 1.7/1.1 = 1.5 experiment Cu/Au v2 ratio phobos 2.6/1.5 = 1.7 3.1/2.1 = 1.5 star v2{2}0-5% 3.7/2.5 = 1.5 5-10% 4.2/3.5 = 1.2 star v2{ftpc} 0-5 3.0/2.1 = 1.4 5-10 3.4/3.4 = 1.0 phenix 0-10% 4.0/3.0 = 1.3 ShinIchi Esumi, Univ. of Tsukuba

  16. V2{2} V2{FTPC} - V2{4} V2{BBC R.P.} PHENIX 200GeV Au+Au 30-40% STAR 200GeV Au+Au 20-60% PHOBOS 200GeV Au+Au 20-40% STAR FTPC and PHENIX BBC have about same acceptance. V2{2} V2{FTPC} V2{AA-pp} PHOBOS 200GeV Cu+Cu 20-40% STAR 200GeV Cu+Cu 20-60% PHENIX 200GeV Cu+Cu ShinIchi Esumi, Univ. of Tsukuba

  17. v1 scaling w.r.t. beam rapidity and v1 wiggle (proton) STAR preliminary Centrality scaling for v1 seems to work better than participant scaling which works for the most of other global variables. This might be trivial if this is only given by participant/spectator shape alone not by the size at all… spectator v1 direction Different trend could be caused by the different pT cut off. anti-flow of p as seen in SPS STAR preliminary PHOBOS ShinIchi Esumi, Univ. of Tsukuba

  18. v2 scaling with mT-m + number of quark (same as hydro at low pT + number of quark) When the mass effect removed by mT-m, only the quark number ratio shows up! Is mass ordering of v2 at low pT generated during or after hadronization? Feed-down for pion is visible in pT, but not in mT-m, because pT(daughter) < pT(parent) , but mT-m(daughter) ~ mT-m(parent) … Decay kinematical effect is masked by the pT to mT-m transformation. ShinIchi Esumi, Univ. of Tsukuba

  19. STAR preliminary v2 scaling with mT-m + number of quark Early freeze-out effect of multi-strangeness hadrons seen in spectra analysis with radial flow does not show up here in v2 analysis, this is an indication that v2 is already built up in early stage. Number of quark scaling is not only the explanation. RQMD Au+Au 200GeV Feng Liu v2 pT (GeV/c) ShinIchi Esumi, Univ. of Tsukuba

  20. jet modification and cone like structure STAR preliminary 0-5% Pb +Au 17GeV pTtrig=2.5-4 GeV/c pTassoc=1-2.5 GeV/c PHENIX nucl-ex/0611019 CERES preliminary 0-12% 200 GeV Au+Au PHENIX Preliminary 10-20% Au+Au 200GeV pTtrig=2.5-4 GeV/c pTassoc=1-2.5 GeV/c STAR preliminary 0-12% Au+Au 200GeV pTtrig=3-4 GeV/c pTassoc=1-2 GeV/c CERES preliminary0-5% Pb +Au 17GeV pTtrig=2.5-4 GeV/c pTassoc=1-2.5 GeV/c The bulk and jet interaction is there, but in Cu+Cu/Au+Au and SPS-RHIC?!? ShinIchi Esumi, Univ. of Tsukuba

  21. PHENIX, nucl-ex/0510019. STAR, PRL93 (2004) 252301. |ftrig-fRP| jet modification and its correlation with v2 jet shape w.r.t. reaction plane geometrical effect of the almond shape This effect itself is a one of v2 sources, which will be an important effect at LHC. This should also lead different v2 between bulk and jet. ShinIchi Esumi, Univ. of Tsukuba

  22. charm quark suppression and flow Charm quark interaction in bulk matter, this makes suppression and collectivity of charm quarks as well as light quarks. ShinIchi Esumi, Univ. of Tsukuba

  23. PHENIX J/y AuAu Central charm hadron AuAu Central strangeness hadron AuAu Central , K, p SQM06, Yifei Zhang more hints of charm quark collectivity N. Xu, SQM 2006, PHENIX (, K, p, J/): PRC69, 034909(04), QM05; STAR (, , ): QM05 PBM et. al. QM06 RHIC SPS SPS J/y would need re-generation, both J/y and open charm spectra are consistent with small transverse radial flow, which might be built up during partonic stage… ShinIchi Esumi, Univ. of Tsukuba

  24. annihilation compton scattering Bremsstrahlung (energy loss) direct photon as a probe of bulk matter Jet-frag. photon from the survived parton v2 > 0 thermal photon v2 > 0 prompt photon v2 = 0 v2 < 0 Inclusive photon v2 presented by STAR consistent with prompt photon production, but we are allowed to speculate, I guess… PHENIX preliminary We just have installed a new reaction plane detector for coming high luminosity Au+Au run7 for rare probe v2 measurement at PHENIX. ShinIchi Esumi, Univ. of Tsukuba

  25. Summary Large number of variables indicate as if there is Quark Gluon Plasma formed at RHIC energies or maybe already at lower energies, however the most of the evidences are still only suggestive, can we look for more direct evidence? ShinIchi Esumi, Univ. of Tsukuba

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