Christina Markert Hot Quarks, Sardinia, Mai 2006 1

Christina Markert Kent State University

• Motivation• Resonance in hadronic phase Time RAA and RdAu Elliptic flow v2• Summary

for the STAR Collaboration

Resonance Production in RHIC Collisions

Christina Markert Hot Quarks, Sardinia, Mai 2006 2

Lifetime of Nuclear Medium

TchemicalTchemical

t > 4 fm/cresonances

Au+Aut ~ 10 fm/c(HBT) Partonic phase < 6 fm/c

C. Markert, G. Torrieri, J. Rafelski, hep-ph/0206260 + STAR delta lifetime > 4fm/c

Christina Markert Hot Quarks, Sardinia, Mai 2006 3

Hot

and

den

se

med

ium

p+p

Au+AuAu+Au interactions:• Extended hot and dense phase• Thermalization at chem. freeze-out• Kinetic freeze-out separated from chemical freeze-out

p+p interactions:• No extended initial medium• Chemical freeze-out (no thermalization)• Kinetic freeze-out close to the chemical freeze-out

Particle yields Particle spectra

time

p

K

p

K

Time in Heavy Ion Reactions

Christina Markert Hot Quarks, Sardinia, Mai 2006 4

Resonance Signals in p+p and Au+Au collisions from STAR

K(892)

(1520)

p+p

p+p

Au+Au

Au+Au (1385)

p+pAu+Au

(1020) p+p

Au+Au

p+p

K(892) K+

(1232) p+ (1020) K + K(1520) p + K(1385) +

Christina Markert Hot Quarks, Sardinia, Mai 2006 5

* and* show rescattering * shows regenerationRegeneration/Rescattering cross section:p)

Interactions of Resonance in Hadronic Nuclear Medium

[1] P. Braun-Munzinger et.al.,PLB 518(2001) 41, priv. communication[2] Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81. M. Bleicher and Horst Stöcker J. Phys.G30 (2004) 111.

Life-time [fm/c] :

Preliminary

UrQMD =10±3 fm/c

Christina Markert Hot Quarks, Sardinia, Mai 2006 6

+X Y

+X Y

+X Y

Regeneration Cross Sections

Regeneration/Rescattering cross section:

Sascha Vogel, San Diego Winter Workshop 2006

Production channel for measured resonances:UrQMD calculations

Christina Markert Hot Quarks, Sardinia, Mai 2006 7

RAA of Resonances (with rescattering)

• K(892) more suppressed in AA than Ks0

• K(892) are lower than Ks0 (and )

pt < 2.0 GeV factor of 2

Christina Markert Hot Quarks, Sardinia, Mai 2006 8

Nuclear Modification Factor RdAu

1. K* is lower than Kaons in low pt d+Au no medium no rescattering why K* suppression in d+Au ?

* follows h+- and lower than protons .

Christina Markert Hot Quarks, Sardinia, Mai 2006 9

Medium in d+Au ?

Preliminary

*: No rescattering in hadronic d+Au mediumK* : Rescattering in hadronic d+Au medium

???

Christina Markert Hot Quarks, Sardinia, Mai 2006 10

Low mean pT ≠ early freeze-out ?

Resonance are regenerating close to kinetic freeze-out we measure late produced (1385)How is elliptic flow v2 effected ?v2= signal for early partonic interactions

Fit to and Higher T kin and lower <T>

Christina Markert Hot Quarks, Sardinia, Mai 2006 11

Effects on v2 of and from Resonances

v2 of pions:1. Primary produced (30%)2. Early resonance decay3. Late resonance decay

v2 of resonances:1. Early resonances2. Regenerated resonances

time

chem

ical

free

ze-

out

p

pp

kine

tic fr

eeze

-out

re-scattering

regeneration

Christina Markert Hot Quarks, Sardinia, Mai 2006 12

Resonances v2 and NCQ Scaling TestEl

lipti

c flo

w v

2

pT (GeV) Fluid dynamics calculations (zero viscosity) describe data pT < 2 GeV Do Resonances show same mass splitting ? Number of Constituent Quark (NCQ) scaling at intermediate pT (2= mesons, 3= baryons) indication of partonic degrees of freedomRegenerated resonances–final state interactions NCQ = 5 (* = + =3+2)

C. Nonaka, et al.,Phys.Rev.C69:031902,2004

Christina Markert Hot Quarks, Sardinia, Mai 2006 13

elliptic flow v2 in minbias Au+Au 200 GeV

2(-)

2( -)

dN

/d(

-)

dN/

d(-

)

signal

Bg of invmass

v2=12±2%

v2=16±0.04%

pT = 1.0-1.5 GeV

Inv mass (K+ K-)

Inv mass (K+ K-)

Elliptic flow

)](2cos[21 2 RvddN

Reaction plane

Kaon p < 0.6 GeV

Christina Markert Hot Quarks, Sardinia, Mai 2006 14

v2 of phi resonance in Au+Au 200GeV

has long lifetime 45fm/c less rescattering or regenerationElliptic flow of Φ-meson is close to Ks Delta resonance ?

STAR PreliminarySTAR Preliminary

Christina Markert Hot Quarks, Sardinia, Mai 2006 15

Summary

• Hadronic resonances help to separate hadronic from partonic lifetime

• Ranking of rescattering over regeneration cross section in medium.

•Low pt RAA behavior confirms rescattering hypothesis. (RdAu puzzle?)

• v2 of long lived resonances seems to follow stable particle trends (confirmation of NCQ scaling)

Christina Markert Hot Quarks, Sardinia, Mai 2006 16

For Raymond

Christina Markert Hot Quarks, Sardinia, Mai 2006 17

Signal Loss in Low pT Region

Inverse slope increase from p+p to Au+Au collisions. UrQMD predicts signal loss at low pT due to rescattering of decay daughters. Inverse slopes T and mean pT are higher.Flow would increase pT of higher masse particles stronger.

pT UrQMD 140 MeV 90 MeV 35 MeV

p+p

Au+Au

K(892)

flowpT

Preliminary

Christina Markert Hot Quarks, Sardinia, Mai 2006 18

Temperature and “Life-time” fromK* and *

Model includes: • Temperature at chemical freeze-out• “Life-time” between chemical and thermal freeze-out• By comparing two particle ratios (no regeneration)

Lambda1520 T= 160 MeV > 4 fm/c K(892) T = 160 MeV > 1.5 fm/c

(1520)/ = 0.039 0.015 at 10% most central Au+Au

K*/K- = 0.23 0.05 at 0-10% most central Au+Au

G. Torrieri and J. Rafelski, Phys. Lett. B509 (2001) 239

Life time:K(892) = 4 fm/c (1520) = 13 fm/c