resonances and correlations in heavy ion c ollisions
DESCRIPTION
Resonances and Correlations in Heavy Ion C ollisions. Christina Markert, Kent State University for the STAR Collaboration. Resonances in Medium Rescattering and Regeneration Hadronic vs Leptonic Decay Resonances at hight p T Conclusions. K -. K *. p +. Au+Au. K -. K *. K * ?. - PowerPoint PPT PresentationTRANSCRIPT
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.