Event anisotropy in highenergy heavyion collisions at RHIC

Event anisotropy in high-energy heavy-ion collisions at RHIC Shin. Ichi Esumi Inst. of Physics, Univ. of Tsukuba elliptic flow and nuclear suppression factor identified hadron v 2 f v 2/RAA(quark coalescence or hydro) electron v 2/RAA(charm quark) inclusive g, p 0 v 2 (direct g v 2/RAA) e (eccentricity) scaling jet correlation and v 2 JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 1

v 2 initial collision geometry x z Non-central Collisions pressure/density gradient, radial/elliptic expansion final momentum anisotropy y reaction plane angle : n x tan(n n) = 2 nd harmonic amplitude : v 2 Σ wi*sin(n i) Σ wi*cos(n i) | i- n| JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 2

y yield (A+A) RAA , RCP R AA = x relative yield in A+A collisions normalized by p+p yield times number of binary collisions R CP = <Ncoll> yield (p+p) yield. Central / <Ncoll>Central yield. Peripheral / <Ncoll>Periheral b Npart : number of participant scaling Ncoll : number of binary collision binary scaling x z 2 x 1=2 3 x 2=6 3 x 3=9 1 x 2=2 impact parameter : b 12 + 11 total 30 collisions total 23 participant nucleons spectators JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 3

spectator directed R. P. Reaction plane detectors MVD SMD/ZDC BBC participant elliptic R. P. JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 4

FBBC 1 -p vs FBBC 2 FSMD 1 -p vs FSMD 2 back-to-back directed plane FSMD-p vs FBBC spectator neutrons vs ps from participants are flowing opposite. neutron spectator charged particles (pions) at mid h [-p, p] F 2 BBC 1 beam vs F 2 BBC 2 reaction plane F 2 MVD 1 vs F 2 MVD 2 F 2 BBC vs F 2 MVD beam line elliptic plane [-p/2, p/2] JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 5

Identified hadron v 2 hydro dynamic behavior at low p. T baryon/meson difference at high p. T QM 05 PHENIX JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba QM 05 STAR 6

f-meson v 2 mass scaling or number of quark scaling? baryon/meson (number of quark) difference hydro dynamic behavior : mf-meson ~ mproton early hadronic freeze-out for multi-strangeness hadrons _ Ξ+Ξ _ Ω+Ω QM 05 PHENIX QM 05 STAR need more data/beam JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 7

Nuclear modification factor : RCP clear separation between baryon group / meson group including f, W, X as well as p, K, p JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 8

Number of quark scaling of v 2 rather good description above 1 Ge. V/c in quark p. T remaining mass dependence at lower p. T region v 2 is already formed during quark phase before hadronization additional hadronic flow might be there after hadronization QM 05 PHENIX JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba QM 05 STAR 9

Non-photonic electron (charm origin) RAA compared with p 0 RAA Non-photonic electron is less suppressed compared with p 0, but it is still a significant suppression RAA~ 0. 3 at higher p. T region 4~5 Ge. V/c (1) q_hat = 0 Ge. V 2/fm (4) d. Ng / dy = 1000 non-photonic electron v 2 is similar with other hadrons at low p. T but smaller at higher p. T region 4~5 Ge. V/c photonic electron v 2 originated from p 0 is above p 0 v 2 at low p. T and similar to p 0 v 2 at high p. T and subtracted already. (2) q_hat = 4 Ge. V 2/fm (3) q_hat = 14 Ge. V 2/fm JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 10

non-photonic electron : charm (+beauty) RAA and v 2 very significant suppression at higher p. T almost same as p 0 suppression above 5 Ge. V/c some difference between experiments at higher p. T which needs to be solved. D-meson flows (+ve v 2), should determine charm v 2 b contribution less suppression less interaction b contribution less flow less thermalized B. Zhang et al. nucl-th/0502056 I’m very much looking forward to hearing following electron v 2 talks!! JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 11

Direct photons are not suppressed RAA is about 1. 0 high p. T, g/p 0 ratio > 1 at high p. T Direct photon contribution is significant at high p. T and at central collisions compared to the inclusive photon yield from the known hadronic sources. JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 12

inclusive g and p 0 v 2 of direct photon gives complimentary information in understanding the origin of binary scaled direct photon production. Bresmsrahlung, because of larger energy loss v 2 < 0 fragmentation in vacuum, from escaped parton v 2 > 0 nucl-ex/0508019 JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 13

try to extract direct g v 2 direct g = R v 2 inclusive g – v 2 b. g. R– 1 v 2 b. g. : expected g v 2 from hadronic decays if v 2 direct g =0 R= v 2 b. g v 2 inclusive g nucl-ex/0508019 JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 14

inclusive g and p 0 v 2 0 -10 % QM 05 : Phenix preliminary run 4 10 -20 % p 0 inclusive g 20 -30 % 30 -40 % 40 -50 % 50 -60 % 0 JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 5 p. T (Ge. V/c) 10 15

Low p. T direct g can be extracted in a different way for both p. T distribution and v 2. better accuracy at low p. T might be expected. JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 16

d. Nch/dh scales with Npart for both Au+Au / Cu+Cu JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 17

RAA scales with Npart for both Au+Au / Cu+Cu JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 18

v 2 does NOT scale with Npart for obvious reason ----- Geometry ----- participant R. P. RQMDv 2. 4 <v 2> (|h|<2) with true R. P. if use all participants to define its axis and its deformation, maximum auto-correlation in e definition? JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba black : Au+Au red : Cu+Cu 19

Participant eccentricity includes initial statistical fluctuation of e and its axis, while experimental v 2 and reaction plane (from participants with the 2 nd moment axis) includes all fluctuations until final particle productions. JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 20

Lesson from PHOBOS should also be considered when comparing between experiments especially for light system. The difference between 2 nd and 4 th order cumulant results differ especially for Cu+Cu. QM 05 PHENIX v 2 RAA jet/HBT(R. P. ) JPS/DNP 2005 Sep. Maui Npart. scaling Ncoll. scaling eecc. scaling Au+Au Cu+Cu Si(Cu)+Au QM 05 STAR Si + Au Shin. Ichi Esumi, Univ. of Tsukuba 238 U + 238 U 21

1 st moment R. P. (SMD/ZDC, BBC, FTPC) e of participant with axis from spectator : yet another e needed? Cu+Cu w. r. t. SMD/ZDC (spectator directed) R. P. needed, it can be different with participant elliptic R. P. Au +Au 200 Ge. V ZDC/SMD spectator v 1 QM 05 PHOBOS spectator directed R. P. ary STAR in prelim QM 05 STAR participant elliptic R. P. JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 22

We should not forget that hadronic cascade can generate apparent number of quark scaling without quark coalescence, although the magnitude of v 2 is about a half of experimental data. ISMD 2005 Ur. QMD origin of this apparent scaling needs to be understood JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 23

High p. T away-side jet suppression softening of associated p. T distribution modification of jet shape at mid-p. T QM 05 : Phenix preliminary JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 24

re-appearance (escaped) of high p. T back-to-back jet p. T(assoc) > 2 Ge. V/c p. T Au+Au, 0 -5% STAR Preliminary JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 25

re-appearance (escaped) of high p. T back-to-back jet centrality PHENIX Preliminary STAR Preliminary 8 < p. T(trig) < 15 Ge. V/c p. T(assoc)>6 Ge. V system/centrality JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 26

PHENIX preliminary jet shape w. r. t. R. P. source of v 2 at high p. T jet yield (a. u. ) v 4 effects need to be considered jet v 2 = b. g. (thermal) v 2 extract jet shape or jet v 2 in-plane pair in between pair out-of-plane pair p. Ttrigger(h) > 3 Ge. V/c 1< p. Tassociated(h) <2 Ge. V/c PHENIX preliminary 0 JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba Df (rad) p 27

proton Summary pion RAA identified particles, f, e+-, g v 2 * partonic flow ? * heavy quark v 2 ? * direct photon production ? 1 electron v 2 photon 0. 1 0 0 p. T jet shape Npart. , Ncoll. , eecc. scaling * test with asymmetric collisions ? jet correlation and v 2 0 * jet shape w. r. t. R. P. or jet v 2 ? JPS/DNP 2005 Sep. Maui Shin. Ichi Esumi, Univ. of Tsukuba 0 |Df| p 28

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