event anisotropy in high-energy heavy-ion collisions at rhic

JPS/DNP 2005 Sep. Maui ShinIchi Esumi, Univ. of Tsukuba 1

Event anisotropy in high-energy heavy-ion collisions at RHIC

ShinIchi Esumi Inst. of Physics, Univ. of Tsukuba

elliptic flow and nuclear suppression factor identified hadron v2

v2/RAA(quark coalescence or hydro) electron v2/RAA(charm quark) inclusive , 0 v2 (direct v2/RAA) (eccentricity) scaling jet correlation and v2


x

zNon-central Collisions

initial collision geometry

pressure/density gradient, radial/elliptic expansion

final momentum anisotropy

Σ wi*sin(ni) tan(nn) = Σ wi*cos(ni)

y

x

reaction plane angle : n

i-n|

2nd harmonic amplitude : v2

v2


2x1=23x2=63x3=93x3=91x2=21x2=2

total 30 collisions12 + 11

total 23 participant nucleons

spectators

Npart : number of participant participant scaling

Ncoll : number of binary collision binary scaling

impactparameter : b

y

x

b

x

z

R AA = yield (A+A)

<Ncoll> yield (p+p)

R CP =yieldCentral / <Ncoll>Central

yieldPeripheral / <Ncoll>Periheral

RAA , RCP

relative yield in A+A collisions normalized by p+p yield times number ofbinary collisions


SMD/ZDC

BBC

Reaction plane detectors

participant elliptic R.P.

spectator directed R.P.

MVD


SMD1vsSMD2BBC1vsBBC2 SMDvs BBC

BBC1vs

BBC2

back-to-back back-to-back spectator neutrons vss from participants are flowing opposite.

MVD1vs

MVD2 BBCvs

MVD

directed plane

elliptic plane

beam linereaction plane

neutron spectator

charged particles(pions) at mid

beam


Identified hadron v2

hydro dynamic behavior at low pTbaryon/meson difference at high pT

QM05 PHENIX QM05 STAR


-meson v2

mass scaling or number of quark scaling?baryon/meson (number of quark) differencehydro dynamic behavior : m-meson ~ mproton

early hadronic freeze-out for multi-strangeness hadrons


Ξ+ΞΩ+Ω

__

need more data/beam


Nuclear modification factor : RCP

clear separation between baryon group / meson group including as well as ,K,p


Number of quark scaling of v2

rather good description above 1GeV/c in quark pT

remaining mass dependence at lower pT regionv2 is already formed during quark phase before hadronizationadditional hadronic flow might be there after hadronization



(3) q_hat = 14 GeV2/fm



(4) dNg / dy = 1000

Non-photonic electron (charm origin) RAA compared with 0 RAA

Non-photonic electron is less suppressed compared with 0, but it is still a significant suppression RAA~ 0.3 at higher pT region 4~5GeV/c

non-photonic electron v2 is similar with other hadronsnon-photonic electron v2 is similar with other hadronsat low pat low pTT but smaller at higher p but smaller at higher pTT region 4~5GeV/c region 4~5GeV/c

photonic electron v2 originated from photonic electron v2 originated from 00

is above is above 00 v2 at low pT and similar to v2 at low pT and similar to 00 v2 at high pT and v2 at high pT and subtracted already.subtracted already.


B. Zhang et al.nucl-th/0502056

non-photonic electron : charm (+beauty) RAA and v2

very significant suppression at higher pT some difference between experiments at higher pT almost same as 0 suppression above 5GeV/c which needs to be solved. D-meson flows (+ve v2), should determine charm v2

b contributionless suppressionless interaction

b contributionless flowless thermalized

I’m very much looking forward to hearing following electron v2 talks!!


Direct photons are not suppressed

RAA is about 1.0 high pT, 0 ratio > 1 at high pTDirect photon contribution is significant at high pT and atcentral collisions compared to the inclusive photon yieldfrom the known hadronic sources.


inclusive and 0 v2

nucl-ex/0508019

v2 of direct photon gives complimentary information in understanding the origin of binary scaled direct photon production.

Bresmsrahlung, because of largerenergy loss v2 < 0

fragmentation

in vacuum, from escapedpartonv2 > 0


try to extract direct v2

v2direct =

R v2inclusive – v2

b.g.

R – 1

v2b.g. : expected v2 from hadronic decays

if v2direct = 0 R =

v2inclusive

v2b.g

nucl-ex/0508019


QM05 : Phenix preliminary run4inclusive and 0 v2

0

inclusive

v2

0 5 pT (GeV/c) 10

0-10 % 10-20 %

30-40 %

50-60 %40-50 %

20-30 %


Low pT direct can be extracted in a different way for both pT distribution and v2.

better accuracy at low pT might be expected.


dNch/d scales with Npart for both Au+Au / Cu+Cu


RAA scales with Npart for both Au+Au / Cu+Cu


<v2> (||<2)

black : Au+Au

red : Cu+Cu

RQMDv2.4

v2 does NOT scale with Npart

for obvious reason

----- Geometry -----

true R.P.

participant R.P.

with true R.P.

if use all participants to define its axis and its deformation, maximum auto-correlation in definition?


Participant eccentricity includes initial statistical fluctuation of and its axis, while experimental v2 and reaction plane (from participants with the 2nd moment axis) includes all fluctuations until final particle productions.


Lesson from PHOBOS should also be considered when comparing between experiments especially for light system.

Npart. scalingNcoll. scalingecc. scaling

Au+AuCu+CuSi(Cu)+Au

v2 RAA jet/HBT(R.P.)

The difference between 2nd and 4th order cumulant results differ especially for Cu+Cu.


238U + 238USi + Au


Au +Au 200 GeV

STAR

prelimi

nary

ZDC/SMD　spectator v1

spectator directed R.P.

participant elliptic R.P.

1st moment R.P. (SMD/ZDC, BBC, FTPC)

of participant with axis from spectator : yet another needed? Cu+Cu w.r.t. SMD/ZDC (spectator directed) R.P. needed, it can be different with participant elliptic R.P.

QM05 PHOBOS

QM05 STAR


ISMD 2005

UrQMD

We should not forget that hadronic cascade can generate apparent number of quark scaling without quark coalescence, although the magnitude of v2 is about a half of experimental data.

origin of this apparent scaling needs to be understood


High pT away-side jet suppression

softening of associated pT distribution

modification of jet shape at mid-pT

QM05 : Phenix preliminary


STAR Preliminary

Au+Au, 0-5%

pT(assoc) > 2 GeV/c

re-appearance (escaped) of high pT back-to-back jet

pT

pT


STAR Preliminary 8 < pT(trig) < 15 GeV/c

pT(assoc)>6 GeV

re-appearance (escaped) of high pT back-to-back jet

centrality

system/centrality

PHENIX Preliminary


0 　　　　　　 (rad)

pTtrigger(h) > 3GeV/c

1< pTassociated(h) <2GeV/c

PHENIX preliminary

jet shape w.r.t. R.P.source of v2 at high pT

v4 effects need to be consideredjet v2 = b.g.(thermal) v2 extract jet shape or jet v2

in-plane pairin between pairout-of-plane pair

jet y

ield

(a.

u.)

PHENIX preliminary


Summary

identified particles, , e, v2

partonic flow ? heavy quark v2 ? direct photon production ?

Npart. , Ncoll. , ecc.scaling

test with asymmetric collisions ?

jet correlation and v2

jet shape w.r.t. R.P. or jet v2 ?

RAAv2

proton pion electron photon

pT pT

1

0

0

0.1

0

0

jet shape


0 1 2 3 4 5

v 2

0.00

0.05

0.10

0.15

0.20

0.25

0.30 s 200 GeVNNAu Au

0SKp

fsTy

5 < Centrality < 30 %

K

(STAR)

(PHENIX)

(STAR)

(PHENIX)

(PHENIX)

event anisotropy in high-energy heavy-ion collisions at rhic

Documents