1 / 28

Strangeness and entropy

Explore the centrality dependence and particle enhancements in Au-Au collisions at different energies, focusing on temperature variations, correlation volume, and entropy considerations. Investigate the flavor dependence of particle yield enhancements and the impact of energy density and entropy on heavy-ion interactions.

sdubois
Download Presentation

Strangeness and entropy

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. Strangeness and entropy

  2. Centrality dependence Solid – STAR Au-Au √sNN = 200 GeV Hollow - NA57 Pb-Pb √sNN = 17.3 GeV STAR Preliminary We can describe p-p and central Au-Au average ratios. Can we detail the centrality evolution? Look at the particle enhancements. E(i) = YieldAA/Npart Yieldpp /2

  3. Centrality dependence STAR Preliminary • Use stat. model info: • C – p-p • Strangeness suppressed • GC – central A-A • Strangeness saturated • Transition describes • E(i) behaviour • T =170-165 MeV • assume same T for p-p and Au-Au Au-Au √sNN = 200 GeV K. Redlich

  4. Centrality dependence Correlation volume: V= (ANN)·V0 ANN = Npart/2 V0 = 4/3 p·R03 R0 = 1.1 fm proton radius/ strong interactions STAR Preliminary T = 170 MeV T = 165 MeV Au-Au √sNN = 200 GeV Seems that T=170 MeV fits data best – but shape not correct K. Redlich

  5. Varying T and R Au-Au √sNN = 200 GeV Calculation for most central Au-Au data Correlation volume: V0  R03 R0 ~ proton radius strong interactions Rapid increase in E(i) as T decreases SPS data indicated R = 1.1 fm K. Redlich

  6. Npart dependence Correlation volume: V= (ANN)a·V0 ANN = Npart/2 V0 = 4/3 p·R03 R0 = 1.2 fm proton radius/ strong interactions STAR Preliminary T = 165 MeV a = 1/3 T = 165 MeV a = 1 T = 165 MeV a = 2/3 Au-Au √sNN = 200 GeV Seems to be a “linear” dependence on collision geometry K. Redlich

  7. More on flavour dependence of E(i) STAR Preliminary PHOBOS: measured E(ch) for 200 and 19.6 GeV Enhancement for all particles? PHOBOS: Phys. Rev. C70, 021902(R) (2004) Au-Au √sNN = 200 GeV Yes – not predicted by model Similar enhancement for one s hadrons

  8. Hagedorn temperature (1965) filled: AA open: elementary [Satz: Nucl.Phys. A715 (2003) 3c • Resonance mass spectrum grows exponentially • Add energy to system produce more and more particles • Maximum T for a system of hadrons. TH ~ 160 MeV TDS = DE increase √s ↔ increase S Blue – Exp. fit Tc= 158 MeV r(m) (GeV-1) Green - 1411 states of 1967 Red – 4627 states of 1996 m (GeV)

  9. Entropy and energy density • Landau and Fermi (50s) • Energy density, e, available for particle creation • Assume S produced in early stages of collision • Assume source thermalized and expands adiabatically • Preserve S • Ideal fluid • S correlated to e via EOS dNch/dh is correlated to S

  10. Entropy and √s • Approximate EOS for that of massless pions. • Assume blackbody • s = S/V related to e s = Fn(√s)

  11. Entropy in Heavy Ion > Entropy in p-p? Nch as measure of entropy J.Klay Thesis 2001 Different EOS? QGP?

  12. Heavy-ion multiplicity scaling with √s There is a scaling over several orders of magnitude of √s i.e. As function of entropy PHOBOS White Paper: Nucl. Phys. A 757, 28

  13. HBT radii <kT>≈ 400 MeV (RHIC)<kT>≈ 390 MeV (SPS) nucl-ex/0505014 Lisa et al. No obvious trends as fn of √s p HBT radii from different systems and at different energies scale with (dNch/dη)1/3 power 1/3 gives approx. linear scale Works for different mT ranges Entropy determines radii

  14. Eccentricity and low density limit PHENIX preliminary v2 different as fn Npart and energy • At hydro. limit v2 saturates • At low density limit Apparent complete failure. Especially at low density! Voloshin, Poskanzer PLB 474 (2000) 27

  15. Fluctuations matter PHOBOS QM2005 Important for all Cu-Cu and peripheral Au-Au

  16. Now see scaling Energy range scanned from √s= 4-200 GeV Again dN/dy i.e. entropy important “low density limit” scaling now works

  17. Strangeness vs entropy L W X Solid – STAR Au-Au √sNN = 200 GeV Hollow - NA57 Pb-Pb √sNN = 17.3 GeV dNch/dh = npp((1-x)Npart/2 + xNbin) npp= Yield in pp = 2.29 ( 1.27) x = 0.13 No scaling between energies But does become ~linear at higher dNch/dh

  18. LHC prediction I 6 5 5.5 TeV 1000 6.4 = RHICx1.6 Most central events: dNch/dh ~1200 PHOBOS White Paper: Nucl. Phys. A 757, 28

  19. LHC prediction II Most central events: dNch/dh ~1200 dNch/dh1/3 ~10.5 Ro = Rs = Rl = 6 fm

  20. LHC prediction III Most central events: dNch/dh ~1200 S ~ 20 But I suspect I’m not in the low density limit any more so v2/e ~ 0.2

  21. LHC prediction IV dNL/dy = dNL/dy ~20-30 dNX/dy = dNX/dy ~4-6 dNW/dy = dNW/dy ~0.5-1 L L W W X X Most central events: dNch/dh ~1200 03

  22. Models readily available to experimentalists

  23. First make a consistency check • Require the models to, in principle, be the same. • Only allow the least common multiple of parameters: T, q, s, s • Use Grand Canonical Ensemble. • Fix weak feed-down estimates to be the same (i.e. at 100% or 0%).

  24. The results Au-Au √sNN = 200 GeV after feed-down increase s decrease T 1  error Similar T and s Significantlydifferent errors. Not identical and feed-down really matters

  25. “Best” predictions (with feed-down) 0-5% Au-Au √sNN = 200 GeV STAR Preliminary

  26. Predictions from statistical model Behavior as expected

  27. Comparison between p-p and Au-Au Au-Au √sNN = 200 GeV STAR Preliminary p-p √s = 200 GeV STAR Preliminary Canonical ensemble

  28. Conclusions • dNch/dh is strongly correlated with entropy • dNch/dh scales as log(√s) • Several variables from the soft sector scale with dNch/dh • HBT • v2 at low densities • Strangeness centrality dependence • Statistical models • Currently differences between models • All get approximately the same results • Also predict little change in strangeness at LHC Soft physics driven by entropy not Npart

More Related