1. Christina Markert Hot Quarks, Sardinia, Mai 2006 1 Christina Markert Kent State University Motivation Resonance in hadronic phase Time R AA and R dAu Elliptic flow v 2 Summary for the STAR Collaboration Resonance Production in RHIC Collisions

2. Christina Markert Hot Quarks, Sardinia, Mai 2006 2 Lifetime of Nuclear Medium T chemical  t > 4 fm/c resonances Au+Au t ~ 10 fm/c (HBT) Partonic phase  < 6 fm/c C. Markert, G. Torrieri, J. Rafelski, hep-ph/0206260 + STAR  delta lifetime > 4fm/c

3. Christina Markert Hot Quarks, Sardinia, Mai 2006 3 Hot and dense medium p+p Au+Au Au+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 yieldsParticle spectra time  p K  p K Time in Heavy Ion Reactions

4. Christina Markert Hot Quarks, Sardinia, Mai 2006 4 Resonance Signals in p+p and Au+Au collisions from STAR K(892)   (1520) p+p Au+Au  (1385) p+p Au+Au  (1020) p+p Au+Au p+p   K(892)  K+   (1232)  p+   (1020)  K + K  (1520)  p + K  (1385)   + 

5. Christina Markert Hot Quarks, Sardinia, Mai 2006 5  * and  * show rescattering  * shows regeneration Regeneration/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 

6. 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

7. Christina Markert Hot Quarks, Sardinia, Mai 2006 7 R AA of Resonances (with rescattering) K(892) more suppressed in AA than K s 0 K(892) are lower than K s 0 (and  ) pt < 2.0 GeV factor of 2

8. Christina Markert Hot Quarks, Sardinia, Mai 2006 8 Nuclear Modification Factor R dAu 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.

9. Christina Markert Hot Quarks, Sardinia, Mai 2006 9 Medium in d+Au ? Preliminary  *: No rescattering in hadronic d+Au medium K* : Rescattering in hadronic d+Au medium ???

10. Christina Markert Hot Quarks, Sardinia, Mai 2006 10 Low mean p T ≠ early freeze-out ? Resonance are regenerating close to kinetic freeze-out  we measure late produced  (1385) How is elliptic flow v 2 effected ? v 2 = signal for early partonic interactions Fit to  and  Higher T kin and lower

11. Christina Markert Hot Quarks, Sardinia, Mai 2006 11 Effects on v 2 of and from Resonances v 2 of pions: 1.Primary produced (30%) 2.Early resonance decay 3.Late resonance decay v 2 of resonances: 1.Early resonances 2.Regenerated resonances time chemical freeze-out   p     p p kinetic freeze-out re-scattering regeneration 

12. Christina Markert Hot Quarks, Sardinia, Mai 2006 12 Resonances v 2 and NCQ Scaling Test Elliptic flow v 2 p T (GeV)  Fluid dynamics calculations (zero viscosity) describe data p T < 2 GeV Do Resonances show same mass splitting ?  Number of Constituent Quark (NCQ) scaling at intermediate p T (2= mesons, 3= baryons)  indication of partonic degrees of freedom Regenerated resonances–final state interactions NCQ = 5 (  * =  +  =3+2) C. Nonaka, et al., Phys.Rev.C69: 031902,2004

13. Christina Markert Hot Quarks, Sardinia, Mai 2006 13  elliptic flow v 2 in minbias Au+Au 200 GeV 2(  -  ) dN/d(  -  )  signal Bg of  invmass v 2 =12±2% v 2 =16±0.04%  p T = 1.0-1.5 GeV Inv mass (K + K - ) Elliptic flowReaction plane Kaon p < 0.6 GeV

14. Christina Markert Hot Quarks, Sardinia, Mai 2006 14 v 2 of phi resonance in Au+Au 200GeV  has long lifetime 45fm/c  less rescattering or regeneration Elliptic flow of Φ-meson is close to Ks Delta resonance ? STAR Preliminary

15. 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 R AA behavior confirms rescattering hypothesis. (R dAu puzzle?) v 2 of long lived resonances seems to follow stable particle trends (confirmation of NCQ scaling)

16. Christina Markert Hot Quarks, Sardinia, Mai 2006 16 For Raymond

17. Christina Markert Hot Quarks, Sardinia, Mai 2006 17 Signal Loss in Low p T Region Inverse slope increase from p+p to Au+Au collisions. UrQMD predicts signal loss at low p T due to rescattering of decay daughters.  Inverse slopes T and mean  p T  are higher. Flow would increase  p T  of higher masse particles stronger.   p T  UrQMD  140 MeV  90 MeV  35 MeV p+p Au+Au K(892) flow  p T  Preliminary

18. Christina Markert Hot Quarks, Sardinia, Mai 2006 18 Temperature and “Life-time” from K* 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