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Baryon Strangeness Correlations: Indicators of a De-Confined Antecedent

Explore the signals of a de-confined antecedent through baryon strangeness correlations in heavy-ion collisions. Differentiate various paradigms including quasi-particle QGP, hadron gas, and bound states. Discuss theoretical and experimental measurements, as well as estimates from lattice and string fragmentation approaches. Conclude with insights on bulk fluctuations of conserved charges and the discernment of experimental observables. Consider the dynamics and existence of bound states in the primordial matter.

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Baryon Strangeness Correlations: Indicators of a De-Confined Antecedent

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  1. Abhijit Majumder Nuclear theory group, Lawrence Berkeley National Lab. Baryon Strangeness correlatons : signals of a de-confined antecedent In collaboration with Volker Koch and Jorgen Randrup

  2. OUTLINE Conserved quantities in HIC Fluctuations of conserved quantities The BS of QGP Differentiating the different paradigms: Quasi-particle QGP, Hadron gas, Bound states, Event Generators Conclusions.. Lattice

  3. The general picture in a Heavy-ion collision What do we know ? Rapid longitudinal expansion… 2) Early thermalization, v2, radial flow… 3) High density matter jet quenching, Bjorken estimates 4) No first order phase transition !

  4. - + - - + - - - + + + - + + + + - - - - - - - - + - + + - + + + + + + + - + - + - + - Imagine a conserved charge carried by a particle in the plasma Net charge conserved in a chosen rapidity interval + + + If nothing drastic happens during hadronization

  5. The BS of the QGP! Quantum numbers conserved in Heavy ion collisions: • Baryon number B (exactly) • Charge Q (exactly) • Strangeness S (almost!) • Combinations are also conserved : BS, QS, BQ etc. • Fluctuations of B,Q,S conserved • Fluctuations of products conserved • Should be conserved in a wide rapidity bin!

  6. BS is carried by  Strangeness carriers  Canonical QGP vs. Hadron gas • BS is carried by s, s • Strangeness carriers s, s B and S locked together in a QGP, But not in a hadron gas, x(-3) as quarks have B=1/3, and S=-1 Correlation in B & S Fluctuations of S

  7. The observable Experimentally: measured in the final state, after freezeout with only final state hadrons... Theoretically: calculated in the initial state, when fluctuations set in, using prevalent degrees of freedom...

  8. Say the fluctuations are set in by independent mobile species Assuming Poisson statistics, s2=<n>, G.C. ensemble To calculate replace event average by average over states... Experimentally, have to use method with no Approx.. BS->p + K

  9. Simple estimates In hadron gas phase • In a QGP phase CBS = 1 At T=170MeV, =0 R = 0.66 Almost 50% rise in CBS from hadron gas to QGP

  10. Hadron gas estimate sensitiveto chemical potential and temperature. Estimate along the freeze-out line Increasing the baryon chemical potential, increases baryons. At large m, S is carried by Kaons and –S by L+S

  11. Estimates from the Lattice Need off-diagonal susceptibilities …’s in unquenched QCD Calculated by R.V. Gavai, S. Gupta, Phys.Rev.D66:094510,2002, But in the quenched approximation At T = 1.5 Tc Off-Diagonal susceptibilities are very small compared to diagonal susceptibilities, CBS = 1+ 0.00(3)/0.53(1)

  12. Full QCD, but with 2 flavors, gives similar insight! From C.R. Alton et. al. Phys.Rev.D71:054508,2005

  13. Estimates from a Bound-State-QGP! E. Shuryak, I. Zahed,Phys.Rev.C70:021901,2004;Phys.Rev.D70:054507,2004. QGP is strongly coupled Large scattering cross-sections Multitude of binary bound states And heavy quasi-particle states of quarks and gluons, m~gT Say fluctuations are set in at 1.5Tc qq is not bound at this temperature Contributing states:

  14. Heavy quark, antiquark quasiparticle have C=1 • Quark-antiquark states: 8  like, 24  like (They have no Baryon number) u s + d s + s u + s d These states have C = 0 • Quark gluon states in triplet color representation 36 states, have C = 1 • Quark gluon states in hexaplet color representation considered unbound at T=1.5Tc All together at T=1.5Tc, CBS = 0.61 Similar to Hadron gas estimate…

  15. Estimate from string fragmentation • Very strongly interacting system • Fluctuations set in by string degrees of freedom • Single string fragmentation: JETSET • Heavy-ion collision : HIJING • Study effect of varying acceptance range in rapidity

  16. Final results, from 4 approaches ! At ymax<y<ymin C = 0 All events have B=0 CBS rises and stabilizes at Smaller range of y Still much smaller than Hadron gas estimate Hadron gas, SZ plasma smaller than naïve QGP or Lattice estimate CBS: discerning experimental observable RQMD from S. Huang

  17. Conclusions/problems • Bulk fluctuations of conserved charges can determine the degrees of freedom • E-by-E measurement of CBS can give insight into the primordial matter. • Strangeness and baryonic degrees of freedom are quasi-particulate • No light meson like bound states! • Experimentally, hard to estimate baryon number: neutrons! • Phase transition causes reshuffling of B & S • Contamination by weak decays from heavier states

  18. Speculations! A) Its still hydro-dynamic i) The dynamics is driven by gluons ii) Quark quasi-particles go along for the ride iii) Need alternative means to determine the existence of bound states! B) Its not hydro-dynamic i) Everything is quasi-particulate, ii) Submerged in a repulsive mean field, iii) Expansion driven by mean field !! ?? A. Peshier, B. Kampfer and G. Soff, Phys.Rev. D66:094003,2002. J. P. Blaizot, E. Iancu and A. Rebhan, Phys.Rev. D63:065003,2001.

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