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System Size and Energy Dependence of Strangeness Production

System Size and Energy Dependence of Strangeness Production. Sevil Salur Yale University for the STAR Collaboration. p T spectra and kinetic freeze-out of particles . Investigation of strange particle yields and ratios. Study of resonances (thermal vs chemical freeze-outs )

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System Size and Energy Dependence of Strangeness Production

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  1. System Size and Energy Dependence of Strangeness Production Sevil Salur Yale University for theSTAR Collaboration

  2. pT spectra and kinetic freeze-outof particles . • Investigation of strange particle yields and ratios. • Study of resonances (thermal vs chemical freeze-outs ) • Comparison of RHIC and SPS yields • Strangeness enhancement (Energy dependence & source type) • RAA comparison with RCP and RdAu • Investigation of strangeness ordering. • Is there a scaling in Au+Au production for the strangequarks? N Participants vs N Binary ? Outline

  3. L (uds)200 GeV Au+Au X (dss)200 GeV Au+Au W (sss)200 GeV Au+Au L 200 GeV p+p X 200 GeV p+p W 200 GeV d+Au X 200 GeV d+Au L 200 GeV d+Au X62 GeV Au+Au W 62 GeV Au+Au L62 GeV Au+Au QM Posters: R. Bellwied, M.Lamont, C.Markert, M.Munhoz&J.Takahashi, J.Speltz L*(1520) (uds) S*(1385) (uus) 200 GeV Au+Au The Corrected Strange ParticleSpectra Y-4 Au+Au and Y-5 Cu+Cu is in progress !

  4. Tkinetic vs Transverse velocity (<T>) 0.13 Most Central Collisions • Temperature Tkinetic is higher for baryons with higher strange quark content for Blast-wave fits. • Spectral shapes are different. T=100 MeV T=132 MeV • p,K, p <T> at 200 GeV > 62 GeV Tkin at 200 GeV =62 GeV • X, W <T> at 200 GeV = 62 GeV Tkin at 200 GeV >62 GeV Tkinetic from a Blast-Wave is not same as the Temperature from a Hydro Model. QM Poster: J.Speltz

  5. STAR Preliminary STAR Preliminary Strange Baryon Production and Collision Energy… Au+Au Pb+Pb STAR Preliminary • s-Baryon production is ~constant at mid-rapidity. • s-Baryon rises smoothly at mid-rapidity. • s-Baryon production equals s-Baryon at RHIC Energies! • s-Baryon Resonance follow the same trend. QM Poster: M.Munhoz&J.Takahashi

  6. S*/L independent of system size at 200 GeV and equal to p+p values at lower energies. Strange ParticleRatios vs System Size L/L ratios are approximately independent of the system size at RHIC energies. Re-scattering and regeneration is needed ! Dt > 0, constant for different centralities! Regeneration σ(K*) > σ(L*) QM Poster: C Markert, D. Mishra

  7. System Size Dependence at 200 GeV Redlich et al. L and X yields in AuAurelative to pp rises. Canonical suppression increases with increasing strangeness L and X arenot flat Correlation volume not well modelled by Npart Is the scaling more important than normalization ?

  8. s-Quarks Have Different Scaling! Scaling according to quark content? u, d – scale with Npart – already observed. s – scale with Nbin – appears better for strange particles. Normalized to central data • K0s – 1/2*Npart + 1/2*Nbin • p – Npart • L – 2/3*Npart + 1/3*Nbin • – 1/3*Npart + 2/3*Nbin • f – Nbin • W – Nbin Does strangeness “see” a significant NBin contribution? Npart f is puzzling! QM Poster: H. Caines

  9. Nuclear Modification Factor Rcp √sNN=62 GeV 0-5% 40-60% 0-5% 40-60% √sNN=200 GeV Y-4 L,K0s Baryon and meson suppression sets in at different pT . 62 GeV Rcp shows less suppression. Baryons and mesons are different ! QM Poster: M.Lamont

  10. Nuclear Modification Factor Rcp 0-5% 40-60% 0-5% 40-60% √sNN=200 GeV Au+Au √sNN=200 GeV Phys. Rev. Lett. 92 (2004) 052302 STAR Preliminary Au+Au √sNN=62 GeV Baryon and meson suppression sets in at same quark pT . √sNN=200 GeV Y-4 L,K0s Baryon and meson suppression sets in at different pT . Coalescence vs Fragmentation?

  11. RAA of Strange Particles 0-5% 0-5% Au+Au p+p Au+Au p+p Au+Au p+p STAR Preliminary STAR Preliminary √sNN=200 GeV √sNN=200 GeV s-quarks scaled with NBin u&d-quarks scaled with Npart f scaled with N Part • s-quarks scaled with NBin • u&d-quarks scaled with Npart • scaled with N Bin Mesons (h+ + h-, K0s, f) follow similar trends. Strange baryons don’t show suppression. Rcp  Raa for strange baryons. Canonical suppression in p+p …? 0-5% STAR Preliminary STAR Preliminary s-quark Ordering with strangeness content! √sNN=200 GeV Particles with strange quarks scale differently than non-strange!

  12. Does entropy drive the strangeness yield? Enhancements are the same or even bigger at RHIC than at SPS ! Is there a universal scaling? Instead of Npart  dNch/dη Correlated to the entropy of the system! SPS and RHIC data follows same curves…

  13. Summary and Conclusions • Transverse velocity T increases with collision energy. TFO(X) > TFO (p) from Blast-wave but TFO(X) = TFO (p) from Hydro • s-Baryon production equals that of s-Baryon at RHIC energies. • Baryon transport is ~ independent of system size at RHIC energies. • Rescattering and regeneration are required to model resonance production. Cross-sections and lifetimes vary (K* vs L*). Dt > 0 between chemical and thermal freezeout for all centralities. • RAA different than RCP - canonical suppression is beinginvestigated in RAA andRdAu . Coalescence can explain the meson baryon difference at 62 GeV collisions too. • Particles with s-quarks appear to scale differently than non-s quarks. Maybe s-quarks “see“ a different correlation volume than light quarks? • Yields scale with dNch/dh for SPS and RHIC (universal scaling?)

  14. 19 D. MishraMeasurement of  D++ and K∗ production in d+Au collisions at √sNN = 200 GeV  33 G. Van BurenThe Ratio S0/L at RHIC 60 R. BellwiedStrange particle production mechanisms in pp collisions at RHIC 61 B. BezverkhnyInitial studies of two particle azimuthal correlations using X baryons in collisions at RHIC 67 L. GaillardIdentified two-hadron correlations at STAR using L, L and K0s with charged hadrons in AuAu at √sNN = 200 GeV  131  H. CainesThe effects of varying the correlation volume on strangeness  146 M. A. Lamont High momentum strange baryon anomalies in heavy ion collisions at RHIC 151  C. MarkertThe influence of medium properties on the resonance production in RHIC collision 152  C. M. MironovSTAR measurements of strange hadron R AuAu and R dAu  155  M. G. Munhoz Measurements of K0s and L production in collisions at  √sNN =  62 GeV Au+Au 163  F. SimonForward L production and nuclear stopping power in d+Au  collisions at RHIC 164  J. SpeltzEnergy dependence systematics of strange and multi-strange particle production 167 A. TangStrangelet search at RHIC  Strange Poster Presentations:

  15. EXTRAS…

  16. Nuclear Modification Factor RdAu d+Au p+p √sNN=200 GeV Cronin Effect might explain R dAu above 1 Less so for mesons than baryons ! Resonances follow a similar trend ! QM Poster: C. Mironov

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