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

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.