# Presentation: 537898

## Baryon Strangeness correlatons : signals of a      de-confined antecedent

- Abhijit Majumder
- Nuclear theory group,
- Lawrence Berkeley National Lab.

- In collaboration with  Volker Koch and Jorgen Randrup

## OUTLINE	

** ****Fluctuations of conserved quantities **
** ****The BS of QGP **
** ****Differentiating the different paradigms: **
** ****Quasi-particle QGP,**
** ****Hadron gas, **
** ****Bound states,**** **
** ****Event Generators**
** ****Conclusions..**

**OUTLINE****	**

**Lattice**

## The general picture in a Heavy-ion collision 

***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 !***

## Imagine a conserved charge carried by a particle in the plasma

**Imagine a conserved charge carried by a particle in the plasma**

**If nothing drastic happens during hadronization **

**Net charge conserved in a chosen rapidity interval****        **

**+**

**+**

**+**

## 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!**

## BS is carried by  s, s

Strangeness carriers  s, s 

**Strangeness carriers  s, s **

- Canonical QGP vs. Hadron gas

**BS is carried by**
**   ******
**Strangeness carriers**
**   ******

**B and S locked together in a QGP, **
**But not in a hadron gas****, **

**Correlation in B & S**

**Fluctuations of S**

**x(-3)  as quarks have B=1/3, and S=-1**

## 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...**

## Assuming Poisson statistics, n>, G.C. ensemble

**Assuming Poisson statistics, ****************n>, G.C. ensemble**

**To calculate replace event average by average over states...**
**Experimentally, have to use method with no**
**Approx.. BS********p + K**

## Simple estimates

- In a QGP phase

***C******BS****** = 1***

- In hadron gas phase

***At T=170MeV,  ************=0***
***R = 0.66***

***Almost 50% rise in C******BS****** from hadron gas to QGP***

## Hadron gas estimate sensitive to chemical potential and temperature. Estimate along the freeze-out line

**Increasing the baryon chemical potential, increases baryons. **
**At large ********S is carried by Kaons **
**and –S by ******

## Estimates from the Lattice

***But in the quenched approximation***

***Need off-diagonal susceptibilities ...************’s  in unquenched QCD***

**At T = 1.5 Tc Off-Diagonal susceptibilities are very small compared to diagonal susceptibilities,  C****BS**** = 1+ 0.00(3)/0.53(1)**

## Full QCD, but with 2 flavors, gives similar insight!

**Full QCD, but with 2 flavors, gives similar insight!**

**From C.R. Alton et. al.  Phys.Rev.D71:054508,2005**

## 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:**

## All together at T=1.5Tc,  CBS = 0.61 

**  ****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,  C****BS**** = 0.61 **
**Similar to Hadron gas estimate...**

## 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

## Final results, from 4 approaches !

**Final results, from 4 approaches**** !**

**At  y****max****<y<y****min****   C = 0**
**All events have ********B=0**
**C****BS**** 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**
**C****BS****: discerning experimental**
**observable**

***RQMD from S. Huang***

## 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

## Speculations!

**B) Its not hydro-dynamic **
**     ****i) Everything is quasi-particulate,**
**    ****ii) Submerged in a repulsive mean field,**
**   ****iii) Expansion driven by mean field !! ??**

**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!**

**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.**** **