1 / 26

What do we learn from Resonance Production in Heavy Ion Collisions ?

What do we learn from Resonance Production in Heavy Ion Collisions ?. Christina Markert, Yale University. Resonances Heavy Ion Collisions Analysis Techniques Time Scale Summary. Hot Quarks 2004, July 18-24, Taos Valley, New Mexico USA. Talks in the Resonance Session.

axel-meyers
Download Presentation

What do we learn from Resonance Production in Heavy Ion Collisions ?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What do we learn from Resonance Production in Heavy Ion Collisions ? Christina Markert, Yale University Resonances Heavy Ion Collisions Analysis Techniques Time Scale Summary Hot Quarks 2004, July 18-24, Taos Valley, New Mexico USA

  2. Talks in the Resonance Session Sevil Salur (Yale):S(1385) Resonance Studies and Pentaquark Search with STAR Debsankar Mukhopadhyay (Vanderbilt U.):fmeson production in Au-Au collisions at sNN = 200 GeV Gene van Buren (BNL):Reconstructing S0 decays in the STAR detector ground state particle ! Hendrik van Hees (Texas A&M University ):Medium Modifications of the Delta Resonance at RHIC Dipali Pal (Vanderbilt U.):f meson production in d-Au collisions at sNN = 200 GeV

  3. Excited state of a ground state particle. • With higher mass but same quark content. • Decay strongly  short life time (~10-23 seconds), • width = natural spread in energy:  = h/t. • Broad states with finite  and t, which can be formed by • collisions between the particles into which they decay. What is a Resonance ? • + p+ + p-  L*(1520) uds ud ud uds p + K-  L*(1520) uud us uds L + p +  S+*(1385) uds ud uus Hadronic and leptonic decay: f  K+ + K- f e+ + e-

  4. Resonance Production and Observation I Elastic and inelastic K-p cross section Data: Bubble chamber, Berkeley 1975 T.S. Mast et at., Phys. Rev. D14 (1976) 14. K- +p  L*(1520)  p- + S+ • Relativistic chiral SU(3) Lagrangian • describe kaon-nucleon scattering • M.F.M. Lutz and E.E. Kolomeitsev • Nucl.Phys.A700 (2002) 193-308 • ---- only s-wave contribution • contribution of s-, p-, d-waves L*(1520) L*(1520) L*(1520) L*(1520) K- beam : plab= 395 MeV (L*(1520))

  5. K*-(892) Number of events 0 2 4 6 8 10 640 680 720 760 800 840 880 920 Invariant mass (K0+p-) [MeV/c2] Resonance Production and Observation II K* from K-+p collision system K- +p  K*-+ p  K0 +p- Luis Walter Alvarez 1968 Nobel Prize for “ resonance particles ” discovered 1960 Bubble chamber, Berkeley M. Alstone (L.W. Alvarez) et al., Phys. Rev. Lett. 6 (1961) 300.

  6. Resonance in Medium I : early stage before chemical freeze-out mass and width II : late stage after chemical freeze-out yield and pT mass and width Survival probability of signals ? Heavy Ion Reaction Time,T, r0 Tch =160 MeV, r0 ~ 0.6 Tkin=100 MeV, r0 ~ 0.2 I II mass and width shift: leptonic channel: particles interact less in hadronic phase hadronic channel: only if less rescattering of resonance or sensitivity to low density (T=100 MeV) yield and pT : leptonic channel: conditions at chemical freeze-out hadronic channel: chemical freeze-out and time scale • Different collision systems p+p and Au+Au, d+Au • (p+p no medium, Au+Au extended medium, d+Au very small medium)

  7. Resonance in Medium I (nuclear matter) Spectral function of L states M.F.M Lutz (SQM 2001) J.Phys.G28:1729-1736,2002 (1520) and S(1385) in medium r= 1r0 (1520): ~100 MeV mass shift and (100 MeV width) S(1385): ~40 MeV mass shift and (50 MeV width)

  8. Resonance in Medium II (nuclear matter) sNN = 200 GeV STAR Preliminary Δ++ 30-50% Au+Au STAR Preliminary Δ++ Width GeV/c2 0.8 ≤pT< 1.4 GeV/c AuAu 0.6 ≤ pT < 1.6 dNch/dη Hendrik van Hees Medium Modifications of the Delta Resonance at RHIC p + nucleon propagation in medium + fireball conditions (T, r) D (1232) inv. mass spectra at Tkin=100 MeV r= 0.12 r0 width increase

  9. p L(1520) K p p L(1520) K Resonance Yields Rescattering and Regeneration) Rescattering Detector Regeneration time chemical freeze out end of inelastic interactions T~170 MeV particle multiplicities thermal freeze out end of elastic interactions T~110MeV particle spectra, HBT Between chemical and kinetic freeze-out Rescattering > Regeneration  Resonance signal loss

  10. Survival probability in a Microscopic Model life time [fm/c]:  <D++<K* <*< *(1520) < *(1530)<  1.3 <1.7 < 4 < 6 < 13 < 20 < 40 S(1385) Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81-87. M. Bleicher and Horst Stöcker J.Phys.G30 (2004) 111. • all decay • - measured chemical freeze-out ~ 5fm/c kinetic freeze-out ~20-30 fm/c (long life time !)

  11. pT changes due to Resonance Rescattering life time [fm/c]:  < D++<K* < *< (1520) <  1.3<1.7 < 4 < 6 < 13 < 40 L(1520) K(892)

  12. f Meson at SPS Hadronic channel: less signal in low pt lower yield • E. Kolomeitsev, SQM2001 • J.Phys.G28:1697-1706,2002 • Rescattering of secondary kaons • Influence of in-medium kaon potential Talks :Debsankar Mukhopadhyay and Dipali Pal fmeson production in Au-Au and d+Au collisions at sNN = 200 GeV

  13. Thermal model in Pb+Pb Ratio = 0.07 for T=170 MeV Pb+Pb ratio = 0.03 T=125 MeV Resonances at CERN SPS (NA49) L*(1520) at SPS Thermal model calculations T=170 MeV Chemical feeze-out

  14. K- p (1520) (1385)  - p - Resonance Reconstruction Energy loss in TPC dE/dx End view STAR TPC p dE/dx K  e momentum [GeV/c] • Identify decay candidates • (p, dedx, E) • Calculate invariant mass K(892)  + K  (1020)  K + K (1520)  p + K S(1385)  L + p X(1530)  X + p

  15. Invariant Mass Reconstruction Invariant mass: (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). STAR Preliminary (1520)

  16. Resonance Signals in p+p STAR Preliminary K(892) Statistical error only STAR Preliminary  Talk by Gene van Buren (ground state particle) (1385) Talk by Sevil Salur

  17. Resonance pT Spectra in p+p at sNN 200 GeV at mid Rapidity K(892) (1520) pT-coverage (yield) pT (integrated) K(892) 95% 680  30  30 MeV (1520) 91% 1080  90  110 MeV dN/dy at |y|<0.5 K(892) = 0.059  0.002  0.004 (1520) = 0.0037  0.004  0.006

  18. Resonance Production in Au+Au Collisions at sNN 200 GeV K*0 • K*0 peak invisible in the same event spectra before background subtraction • due to huge combinatorial background. • Background comes from mis-identified correlated particles

  19. K*0 + K*0 STAR Preliminary Au+Au minimum bias pT  0.2 GeV/c |y|  0.5 Statistical error only Resonance Production in Au+Au Collisions at 200 GeV at mid Rapidity (1520) K(892) STAR Preliminary dN/dy at y=0 central Au+Au K(892)+Anti-K(892)/2 = 10.2  0.5  1.6 (1020) = 7.70  0.30  10% (1520) = 0.58  0.21  40% (assuming T=350-450MeV) (1020) STAR Preliminary

  20. p L* K p p L* K Time Scale • p+p interactions: • No extended initial medium • Chemical freeze-out (no thermalisation) • Kinetic freeze-out close to the chemical freeze-out p+p Tch, mb Tkin, b Particle yields Particle spectra Au+Au • Au+Au interactions: • Extended hot and dense phase • Thermalisation at chem. freeze-out • Kinetic freeze-out separated from • chemical freeze-out Hot and dense medium time

  21. Resonance Suppression STAR Preliminary Statistical Model for Particle Production in p+p and Au+Au Collision p+p at 200 GeV Au+Au at 200 GeV In pp particle ratios are well described with T=160 MeV Resonance ratios in Au+Au are not are well described with Tch = 16010 MeV, mB = 24 5 MeV (Olga Barannikova) • Also: • F. Becattini, Nucl. Phys. • A 702, 336 (2002)

  22. Resonance Production in p+p and Au+Au Life time [fm/c] :  (1020) = 40 L(1520) = 13 K(892) = 4 ++ = 1.7 r (770) = 1.3 Thermal model [1]: T = 177 MeV mB = 29 MeV UrQMD [2] [1] P. Braun-Munzinger et.al., PLB 518(2001) 41 D.Magestro, private communication [2] Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81. M. Bleicher and Horst Stöcker .Phys.G30 (2004) 111. p+p ratios are consistent with thermal model prediction T=160 MeV Rescattering and regeneration is needed ! • F. Becattini, Nucl. Phys. A 702, 336 (2002)

  23. K(892) K(892) Au+Au Au+Au p+p p+p STAR Preliminary STAR Preliminary K(892) Proton Centrality pT (GeV/c) pT (GeV/c) 0% - 10% 1.080  0.120 1.090  0.110 50% - 80% 1.030  0.120 0.760  0.050 pp 0.680  0.040 0.620 0.040 Signal Loss in low pT Region Signal loss of ~70% for K(892) 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 (Dt 5-20fm/c)

  24. preliminary More resonance measurements are needed to verify the model and lifetimes Temperature, Lifetime and Centrality Dependence from L(1520)/L and K(892)/K G. Torrieri and J. Rafelski, Phys. Lett. B509 (2001) 239 Life time: K(892) = 4 fm/c L(1520) = 13 fm/c • Model includes: • Temperature at chemical freeze-out • Lifetime 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

  25. Temperatures and lifetimes from Particle Spectra p,K and p Tch freeze-out Tkin and b from Blast-Wave-Fit to p, K and p Tch from Thermal model Hhh ff Tkin freeze-out Dt (Tch /Tkin –1) R/b Lifetime nearly constant in peripheral and central Au+Au collisions

  26. Summary • Resonances can be measured in heavy ion collisions • K(892)/K and L(1520)/L ratios are smaller in A+A than in p+p collisions (SPS and RHIC). • Thermal model predictions are higher than measured K(892)/K and L(1520)/L. Rescattering and regeneration in hadronic source after chemical freeze-out Results from leptonic channel from SPS gives same answer. RHIC ? Au+Au Dt > 4 • Lifetime between chemical and thermal freeze-out Dt > 4 fm/c • Small centrality dependence in K(892)/K and L(1520)/L ratios. Suggest nearly same lifetime (Dt) for peripheral and central Au+Au collisions. • Consistent with observation of stabile particle yields and spectra (p,K,p)

More Related