Resonances and Correlations in Heavy Ion C ollisions

Christina Markert Breckenridge, Feb 6-11, 2005 1

Christina Markert, Kent State University

for the STAR Collaboration

Resonances in Medium

Rescattering and Regeneration

Hadronic vs Leptonic Decay

Resonances at hight pT

Conclusions

Resonances and Correlations in Heavy Ion Collisions

Christina Markert Breckenridge, Feb 6-11, 2005 2

Resonances in Medium

Chemical freeze-out

Thermal freeze-out

Au+Au

Hadronization

+

+

Rescattering/regeneration

?

HadronizationHadrons are formed from quarksChemical freeze-out: T~170MeV end of inelastic interactionsparticle yieldsKinetic freeze-out: T~100MeVend of elastic interactionsparticle spectra

Proposed measurementsCollision systems:p+p and A+A collisionsLeptonic and hadronic channels:e.g. e++e- , ++- , K+

+K-

Christina Markert Breckenridge, Feb 6-11, 2005 3

Resonance Reconstruction in STAR TPC

Energy loss in TPC dE/dx

momentum [GeV/c]

dE/dx

p

K

e(1385)

-

-

p

(1520)

K- p

K(892) + K

(1020) K + K

(1520) p + K

(1385) + +

End view STAR TPC

• Identify decay candidates (p, dedx, E)• Calculate invariant mass

Christina Markert Breckenridge, Feb 6-11, 2005 4

Resonance Signals in p+p and Au+Au Collisions

K(892)

(1385)ΦK+K-

(1020)(1520)

p+p

Au+Au

STAR Preliminary

Christina Markert Breckenridge, Feb 6-11, 2005 5

Resonance momentum Spectra

Integrated momentum distribution yields

K(892) (1385) and (1520)

STAR Preliminary

Christina Markert Breckenridge, Feb 6-11, 2005 6

Rescattering and Regeneration Thermal model

UrQMD

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

* and* show rescattering and* show regenerationRegeneration cross section:p) p

Life-time [fm/c] :++ = 1.7 K(892) = 4 =(1520) = 13 (1020) = 45

Christina Markert Breckenridge, Feb 6-11, 2005 7

Particle spectra from Thermal Model

Signal loss for K* in low momentum region due to rescattering Regeneration also in low momentum region ()

T = 165.7 MeV

μB = 27.9 MeV

W. Florkowski, SQM2004

Christina Markert Breckenridge, Feb 6-11, 2005 8

Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81-87. M. Bleicher and Horst Stöcker .Phys.G30 (2004) 111.

pTUrQMD

100 MeV

K(892) 140 MeV

35 MeV

Signal Loss in low pT Region (UrQMD)

pT spectrum flatter increase of <pT>

Christina Markert Breckenridge, Feb 6-11, 2005 9

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 and mean pT are higher. UrQMD has long lifetime ( 5-20fm/c)

pT changes due to rescattering ?

ppAuAu

pT UrQMD

100 MeV

K(892) 140 MeV

35 MeV

Christina Markert Breckenridge, Feb 6-11, 2005 10

“Life-time” from Resonances

“Life-time” nearly constant in

peripheral and central Au+Au collisions

Resonances with more rescattering than regeneration: K*, (1520) > 4 fm/c

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

Tch from thermal model fit,Tkin from Blast-Wave-Fit to , K and p

Tch freeze-out

Tkin freeze-out

Christina Markert Breckenridge, Feb 6-11, 2005 11

Meson at SPS

Hadronic channel: less signal in low ptlower yield (factor 4±2)

CERES: K+K-, e+e- [A. Marin SQM2004]

Rob Veenhof

T (

MeV

) NA49 Pb-Pb

NA50 Pb-PbNA60 In-In

+-

Christina Markert Breckenridge, Feb 6-11, 2005 12

Hadronic Phase after Chemical Freeze-out

• Signal loss in UrQMD = 26%• Data: yield factor of 4±2 difference for hadronic to leptonic channel.• Additional in medium modification of resonance at early stage ?

UrQMD: K*(892) (1520)

SPS (17 GeV) 66% 50% 26%

RHIC (200GeV) 55% 30% 23%

Theory can describes data:K. Haglin et. al, E. Kolomeitsev et.al

• shorter lifetime in medium• decay rate increased with in-medium kaons +- from early decay +- from late decay

signal loss in low momentum region Increase of inverse slope

Christina Markert Breckenridge, Feb 6-11, 2005 13

Decaytime for Hadronic vs Leptonic Channel

UrQMD

l+l-

+-

- all decay- measured

Short lifetime resonances:Leptonic signal signal from early decayHadronic signal signal from late decay ( later than)

- all decay- measured

Christina Markert Breckenridge, Feb 6-11, 2005 14

• can re-created until end of the reaction (T kin ~ 90MeV)

• re-creation is only possible near chemical freeze-out

Estimate the Regeneration Probability

Tmms

2

3221

Estimate of available energy for re-feeding at different reaction stages:

Marcus Bleicher, SQM2004

Christina Markert Breckenridge, Feb 6-11, 2005 15

Delta Resonance from late decay

STAR preliminary30-50% Au+Au

Δ++

+nucleon propagation in medium + fireball conditions (T, )

(1232) from: Tkin=100 MeV (1232) width increase

Δ+

+ W

idth

G

eV

/c2

dNch/dη

STAR PreliminarysNN = 200 GeV

AuAu

Minv p+ [GeV/c2]

Hendrik von Hees: HotQuarks2004(Hees and Rapp nucl-th/0407050)

PDG

Christina Markert Breckenridge, Feb 6-11, 2005 16

Feed down from Resonances

J.Letessier, J.Rafelski, Hadrons and Quark Gluon Plasma, Cambridge Monographs

direct

Tch = 160 MeV

Thermal model+STAR data Tch=160 MeV 32% primary Lambdas ~30% primary Protons

Large fraction of stable particles come from resonance decays.

Rescattering and regeneration Less primary particlesMomentum distribution changes

STAR

Regeneration increases the number of primary particles that get used by a resonance

p

pp

2 measured ’s are coming from decays

See also Levente Molnar’s talk

Christina Markert Breckenridge, Feb 6-11, 2005 17SQM2004 - Cape Town – September 2004 [email protected]

STAR PRELIMINARYAu+Au at Au+Au at √s√sNNNN==200GeV200GeV

, freeze out earlier ?

Kinetic freeze-out

Christina Markert Breckenridge, Feb 6-11, 2005 18

Regeneration of (1530)? see late

+ (1530)regeneration cross section ?

Large regeneration cross sectionFor and (1385)

Christina Markert Breckenridge, Feb 6-11, 2005 19

Resonances from Jets in p+p ?

Thermal <pT> prediction for T = 170 MeV, =0 High mass particles from more jet like events

Christina Markert Breckenridge, Feb 6-11, 2005 20

Resonances in Medium (Jets vs Bulk Matter)

Resonances as:• Particle in jet• Bulk particlesame side/away side

Resonance from bulk

Resonance in jet

High luminosity, large acceptance,particle id up to 30 GeV.

RHIC II (idea of a new detector R2D) Talks by Angelika Drees,Rene Bellwied and John Harris

Snap shot from early stage

of collision

Christina Markert Breckenridge, Feb 6-11, 2005 21

Conclusions

• Strong interacting hadronic medium after chemical freeze-out. Thermal models do not describe all resonance yields. Rescattering and regeneration of resonances. Regeneration probes hadronic cross sections of heavy baryons. “Life-time” between freeze-outs > 4 fm/c

• Medium modification of resonances. yield in leptonic and hadronic channel at SPS may give indication of width broadening of phi in medium. Width broadening of observed at RHIC energies in Au+Au collisions.

• Large fraction of particles coming from resonance decays Could affect kinematics of ’primordial’ particles.

• High pT Resonances my probe the medium at early stage.