1. Christina MarkertHirschegg, Jan 16-22, 2005 1 Resonance Production in Heavy Ion Collisions Christina Markert, Kent State University Resonances in Medium Rescattering and Regeneration Time Scale Phi Puzzle at SPS Conclusions

2. Christina MarkertHirschegg, Jan 16-22, 2005 2 Resonances in Medium Life-time [fm/c] :  ++ = 1.7 K(892) = 4  =   (1520) = 13  (1020) = 44 Chemical freeze-out Thermal freeze-out Au+Au Hadronization time space  ++   ++  Rescattering/regeneration ?? Hadronization Hadrons are formed from quarks Chemical freeze-out: T~170MeV end of inelastic interactions particle yields Kinetic freeze-out: T~100MeV end of elastic interactions particle spectra

3. Christina MarkertHirschegg, Jan 16-22, 2005 3 Rescattering and Regeneration Proposed measurements Collision systems: p+p and A+A collisions Leptonic and hadronic channels: e.g.   e + +e -,  + +  -, K + +K - Life-time [fm/c] :  = 1.3  ++ = 1.7 K(892) = 4.0  =   (1520) = 13  (1020) = 45 time chemical freeze-out            signal lost kinetic freeze-out signal measured late decay signal measured rescattering regeneration  e+e+ e-e- signal measured early decay  ++ -- signal measured late decay

4. Christina MarkertHirschegg, Jan 16-22, 2005 4 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

5. Christina MarkertHirschegg, Jan 16-22, 2005 5 Invariant Mass Reconstruction in p+p  (1520) STAR Preliminary  (1520) — original invariant mass histogram from K - and p combinations in same event. — normalized mixed event histogram from K - and p combinations from different events. (rotating and like-sign background) Extracting signal: After Subtraction of mixed event background from original event and fitting signal (Breit-Wigner). Invariant mass:

6. Christina MarkertHirschegg, Jan 16-22, 2005 6 Resonance Signal in p+p collisions STAR Preliminary Statistical error only K(892)  (1385)  STAR Preliminary ΦK+K-ΦK+K- p+p STAR Preliminary p+p Δ ++ Invariant Mass (GeV/c 2 )

7. Christina MarkertHirschegg, Jan 16-22, 2005 7 Resonance Signal in Au+Au collisions STAR Preliminary Au+Au minimum bias K *0 + K *0  (1520) STAR Preliminary  (1020) STAR Preliminary  *± +  *±  K(892)  (1385)

8. Christina MarkertHirschegg, Jan 16-22, 2005 8 Resonance momentum Spectra Integrated momentum distribution  yields K(892)  (1385) and  (1520)

9. Christina MarkertHirschegg, Jan 16-22, 2005 9 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 regeneration Regeneration cross section:  p)   p     Life-time [fm/c] :  ++ = 1.7 K(892) = 4  =   (1520) = 13  (1020) = 45

10. Christina MarkertHirschegg, Jan 16-22, 2005 10 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 μ B = 27.9 MeV W. Florkowski, SQM2004

11. Christina MarkertHirschegg, Jan 16-22, 2005 11 p T changes due to rescattering (UrQMD) [MeV]T allT obs  p T  all  p T  obs  pT pT  125190490640150    250230665765100 K(892)160230550690140  (1385)20024073082090  23025084587035  17519061064535 K(892)  (1520) Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81-87. M. Bleicher and Horst Stöcker.Phys.G30 (2004) 111.

12. Christina MarkertHirschegg, Jan 16-22, 2005 12 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 and mean p T are higher. UrQMD has long lifetime (  5-20fm/c)  p T  UrQMD    100 MeV K(892)140 MeV  35 MeV

13. Christina MarkertHirschegg, Jan 16-22, 2005 13 Temperature and “Life-time” from K* and  * (STAR) Model includes: Temperature at chemical freeze-out “Life-time” between chemical and thermal freeze-out By comparing two particle ratios (no regeneration) results between : T= 160 MeV =>  > 4 fm/c (lower limit !!!)  = 0 fm/c => T= 110-130 MeV  (1520)/  = 0.034  0.011  0.013 K*/K - = 0.20  0.03 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 Does not work for  *,  ++,  STAR 

14. Christina MarkertHirschegg, Jan 16-22, 2005 14 Temperature, “Life-time” from Particle Spectra ,K and p T ch freeze-out T kin freeze-out T ch from Thermal model, T kin and  from Blast-Wave-Fit to , K and p “Life-time” nearly constant in peripheral and central Au+Au collisions  t  (T ch /T kin –1) R/  Hhh ff Go to smaller systems volume  “Life-time” d+Au, Si+Si, Cu+Cu

15. Christina MarkertHirschegg, Jan 16-22, 2005 15  Meson puzzle at SPS Hadronic channel: less signal in low pt lower yield (factor 2-4) CERES:   K + K -, e + e - [A. Marin SQM2004] Carlos Lourenço Yield?

16. Christina MarkertHirschegg, Jan 16-22, 2005 16 Hadronic Phase after Chemical Freeze-out Signal loss in UrQMD = 26% Data: yield factor of 2-4 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 UrQMD: Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81. M. Bleicher and Horst Stöcker.Phys.G30 (2004) 111. signal loss in low momentum region  Increase of inverse slope

17. Christina MarkertHirschegg, Jan 16-22, 2005 17 Time from Hadronic and Leptonic Channel UrQMD l+l-l+l- +-+- - all decay - measured Leptonic signal  signal from early decay Hadronic signal  signal from late decay

18. Christina MarkertHirschegg, Jan 16-22, 2005 18 Delta Resonance in dense Matter STAR preliminary 30-50% Au+Au Δ ++  +nucleon propagation in medium + fireball conditions (T,  )  (1232) from: T kin =100 MeV  (1232)  width increase Δ ++ Width GeV/c 2 dN ch /dη STAR Preliminary  s NN = 200 GeV AuAu M inv p+  [GeV/c 2 ] Hendrik von Hees: HotQuarks2004 (Hees and Rapp nucl-th/0407050) Medium Modifications of the Delta Resonance at RHIC PDG

19. Christina MarkertHirschegg, Jan 16-22, 2005 19 Feed down from Resonances Thermal model+STAR data T ch =160 MeV  32% primary Lambdas  26% primary Protons Regeneration increases the number of primary particles that get used by a resonance ProtonsLambdas Lambda Delta 00 direct ** 00  % of total yield  p     p p 2 measured  ’s are coming from  decays Large fraction of stable particles come from resonance decays. Rescattering and regeneration  Less primary particles  Momentum distribution changes

20. Christina MarkertHirschegg, Jan 16-22, 2005 20 Resonances from Jets in p+p ? Thermal prediction for T = 170 MeV,  =0 High mass particles from more jet like events

21. Christina MarkertHirschegg, Jan 16-22, 2005 21 Resonances in Medium (Jets vs Bulk Matter) Resonances as: Particle in jet Bulk particle same side/away side Resonance from bulk Resonance in jet High luminosity, large acceptance, particle id up to 30 GeV. R2D detector for RHIC II Talk by Rene Bellwied Snap shot from early stage of collision

22. Christina MarkertHirschegg, Jan 16-22, 2005 22 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 give indication of width broadening of phi in medium.  Width broadening of    observed at RHIC energies in Au+Au collisions  medium modification. Large fraction of particles coming from resonance decays  Could affect kinematics of ’primordial’ particles.