Thermal properties of light mesons from holography

TL;DR

This paper investigates the thermal behavior of light mesons using a holographic AdS/QCD model, revealing how their masses, widths, and chiral partner degeneracy evolve with temperature, indicating meson dissociation and chiral symmetry restoration.

Contribution

It provides a detailed holographic analysis of meson thermal properties, including screening and pole masses, widths, and chiral partner behavior, at finite temperature.

Findings

Screening masses of $\

Pole masses have minima at low T and increase at high T.

Thermal widths increase rapidly above $T_{cp}$, indicating meson dissociation.

Abstract

The thermal properties of light mesons, including the temperature dependence of their masses (both screening and pole masses) and thermal widths, are studied in a two-flavor ($N_f=2$) soft-wall AdS/QCD model. By solving the spatial correlation functions, we extract the screening masses ($m_{\rm{scr}}$) from their poles. The screening masses of pseudo-scalar ($\pi$) and axial-vector ($a_1$) mesons increase almost monotonously with the increase of temperature. The screening masses of scalar ($\sigma$) and vector ($\rho$) mesons decrease at low temperature and increase at high temperature. The pole masses ($m_{\rm{pole}}$) and the thermal widths ($\Gamma$) are extracted from the temporal correlation functions and the corresponding spectral functions. The results indicate that the pole masses have local minima at low temperature and increase at high temperature. The thermal widths increase rapidly above the chiral crossover temperature $T_{cp}$, indicating the dissociations of mesons at high temperature. Furthermore, the degeneration of the chiral partners ($\pi$ and $\sigma$, $\rho$ and $a_1$) above $T_{cp}$ is observed from the screening and pole masses, revealing the chiral symmetry restoration at the hadronic spectrum level. Finally, we numerically verify that the spectral functions in the temporal regime are strongly related to the quasi-normal modes with complex frequencies $\omega_0=m_{\rm{pole}}-i \Gamma/2$.