# Quark Matter 2012

12-18 August 2012
US/Eastern timezone

## From dileptons to chiral symmetry restoration: Sum rules and the axial-vector spectral function.

16 Aug 2012, 16:00
2h

Poster QCD at finite temperature and density

### Speaker

Paul Hohler (Texas A&M University)

### Description

The medium modifications of vector and axial-vector spectral functions are investigated using Weinberg and QCD sum rules in an attempt to establish chiral symmetry restoration. Such a study is essential for the interpretation of a pertinent signal from dilepton data in heavy-ion collisions. We start from vacuum spectral functions which include both ground- and excited-state resonances for both the vector and axial-vector channels, supplemented by an identical perturbative continuum. The vacuum spectral functions are constructed to agree with tau decay data and Weinberg sum rules. In the medium, the rho spectral function is taken from effective hadronic many-body theory which is consistent with available dilepton data. The in-medium properties of the rho' are constrained by satisfying the in-medium QCD sum rule. For the axial-vector channel, different ansaetze are chosen for the in-medium a1 (broadening, mass drop, two-level model), while the medium modification of the excited state is again constrained by the QCD sum rule. These different ansaetze are then tested for chiral symmetry restoration through the Weinberg sum rules.

### Primary author

Paul Hohler (Texas A&M University)

### Co-author

Ralf Rapp (Texas A&M University)

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