# Quark Matter 2012

12-18 August 2012
US/Eastern timezone

## Beam Energy Dependent Charge Balance Functions in Heavy Ion Collisions at STAR

16 Aug 2012, 16:00
2h

Poster Exploring the QCD phase diagram

### Speaker

Hui Wang (Michigan state university)

### Description

The study of correlations between opposite sign charge pairs can provide a powerful tool to probe the properties of the quark-gluon plasma (QGP). The balance function, which measures the correlations between opposite sign charge pairs, is sensitive to the mechanisms of charge formation and the subsequent relative diffusion of the balancing charges. The study of the balance function can provide information about charge creation time as well as the subsequent collective behavior of particles. We will present charge balance function results for relative pseudorapidity and azimuthal angle from Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7 to 200 GeV from the recent RHIC beam energy scan. Results from new measurements of balance function at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV are added to the suite of observations. We will also present balance function results in terms of relative rapidity and Lorentz invariant momentum difference between the two particles for identified pions, kaons and protons using STAR Time Of Flight (TOF) detector. The normalized balance function width ($W$ parameter)~\cite{NA49_balance_2007} is applied to compare different experimental measurements of the width of the balance function in terms of relative pseudorapidity. UrQMD transport model calculations are also compared with data. \bibitem{NA49_balance_2007} C. Alt {\it et al.} [NA49 Collaboration], Phys. Rev. C {\bf 76}, 024914 (2007).

### Primary author

Hui Wang (Michigan state university)

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