Massive Yang-Mills for Vector and Axial-Vector Spectral Functions at Finite Temperature

Abstract

The hadronic mechanism which leads to chiral symmetry restoration is explored in the context of the rho-pi-a_1 system using Massive Yang-Mills, a hadronic effective theory which governs their microscopic interactions. In this approach, vector and axial-vector mesons are implemented as gauge bosons of a local chiral gauge group. We have previously shown that this model can describe the experimentally measured vector and axial-vector spectral functions in vacuum. Here, we carry the analysis to finite temperatures by evaluating medium effects in a pion gas and calculating thermal spectral functions. We find that the spectral peaks in both channels broaden along with a noticeable downward mass shift in the a_1 spectral peak and negligible movement of the rho peak. The approach toward spectral function degeneracy is accompanied by a reduction of chiral order parameters, i.e., the pion decay constant and scalar condensate. Our findings suggest a mechanism where the chiral mass splitting induced in vacuum is burned off. We explore this mechanism and identify future investigations which can further test it.

28 pages, 24 figures

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• The STAR Dilepton Physics Program
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Cited by in corpus (9)

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• In-Medium Spectral Functions of Vector- and Axial-Vector Mesons from the Functional Renormalization Group
• Thermal Electromagnetic Radiation in Heavy-Ion Collisions
• Fluctuating vector mesons in analytically continued FRG flow equations
• Spectral functions and in-medium properties of hadrons
• Electromagnetic and weak probes: theory
• Masses of the lowest spin-0 and spin-1 meson nonets: explicit symmetry breaking effects
• Electric conductivity of hot pion matter