Thermal Mass Spectra of Vector and Axial-Vector Mesons in Predictive Soft-Wall AdS/QCD Model

TL;DR

This paper extends the soft-wall AdS/QCD model to finite temperature to study the thermal behavior of vector and axial-vector mesons, revealing how their spectral peaks diminish and vanish at the deconfinement temperature.

Contribution

It introduces a modified bulk scalar potential and dilaton solution to accurately compute meson spectral functions at finite temperature within the soft-wall AdS/QCD framework.

Findings

Spectral peaks shift to lower mass and broaden with increasing temperature.

Peaks disappear at the critical temperature around 200 MeV, indicating deconfinement.

Quantitative analysis of peak dissolution using Breit-Wigner fits.

Abstract

We extend the predictive soft-wall AdS/QCD model to a thermodynamic model by considering the black hole metric. A modified bulk vacuum expectation value and a modified coefficient for the quartic term in the bulk scalar potential are introduced to obtain a smooth dilaton solution for computing the spectral functions of the vector and axial-vector mesons. It is demonstrated that the peaks appearing in the spectral functions characterize the thermal mass spectra of vector and axial-vector mesons, where the location of the peak moves to a lower value and the width of the peak becomes wider when increasing the temperature. We observe that the peak disappears completely at the critical temperature around $T_c=200$ MeV, which implies the deconfinement of quark and the restoration of chiral symmetry breaking. A numerical study by fitting the spectral function in terms of the Breit-Wigner form has been made to show how the peak dissolves quantitatively when the temperature is increased to the critical point.