# Quark Matter 2012

12-18 August 2012
US/Eastern timezone

## Clustering of Color Sources and the Temperature Dependence of Shear Viscosity of the QGP in Central A-A Collisions at RHIC and LHC Energies

16 Aug 2012, 16:00
2h

Poster Exploring the QCD phase diagram

### Speaker

Dr brijesh srivastava (Purdue University)

### Description

The shear to viscosity ratios ($\eta/s$) are obtained for the QGP in the context of the Color String Percolation Model (CSPM) using data produced in Au-Au collisions at $\sqrt{s_{NN}}$ = 200 A GeV at RHIC and Pb-Pb at $\sqrt{s_{NN}}$ = 2.76 TeV at LHC \cite{per}. The experimental transverse momentum spectrum is used to measure the percolation density parameter $\xi$ in Au-Au collisions (STAR)\cite{eos}. The relativistic kinetic theory relation for $\eta/s$ is evaluated using CSPM values for the temperature and the mean free path of the QGP constituents \cite{gul1}. For Pb-Pb at $\sqrt{s_{NN}}$ = 2.76 TeV, $\xi$ values are obtained from the extrapolation at RHIC energy. The value of $\eta/s$ is 0.204$\pm$ 0.020 and 0.262$\pm$0.026 at the initial temperatures of 193.6 MeV (RHIC) and 262.2 MeV (LHC), respectively. These values are 2.3 and 3.2 times the AdS/CFT conjectured lower bound $1/4\pi$ but are consistent with the theoretical estimates of strongly coupled QGP.

### Primary author

Dr brijesh srivastava (Purdue University)

### Co-authors

Dr Andy Hirsch (Purdue University) Jorge Dias de Deus (Instituto Superior Tecnico) Dr Rolf scharenberg (Purdue university) carlos Pajares (University Santiago)

### Presentation Materials

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