Properties of kaon at non-zero temperature and baryon chemical potential

TL;DR

This study explores how the mass and decay constant of kaons change in hot and dense quark matter, revealing significant variations with temperature and baryon chemical potential, relevant for understanding matter under extreme conditions.

Contribution

It provides a detailed analysis of kaon properties at finite temperature and baryon density using QCD sum rules, including non-perturbative effects up to dimension five.

Findings

Kaon mass increases with baryon chemical potential up to ~0.4 GeV, then decreases and vanishes near 1.1 GeV.

Decay constant decreases with baryon chemical potential up to ~0.4 GeV, then increases at finite temperatures.

Mass and decay constant are stable up to certain temperatures, then vary significantly beyond those points.

Abstract

We investigate the spectroscopic properties of the strange particle kaon in the framework of hot and dense QCD. To this end, first, we find the perturbative spectral density, which is connected with both the temperature $T$ and the baryon chemical potential $\mu_{B}$. We include the non-perturbative operators as functions of temperature and baryon chemical potential up to mass dimension five. We perform the calculations in momentum space and use the quark propagator in the hot and dense medium. The numerical results at non-zero temperature and baryon chemical potential demonstrate that the mass of the particle rises considerably by increasing the baryon chemical potential at a fixed temperature (for both the zero and non-zero temperatures) up to approximately $\mu_{B}=0.4$ GeV. After this point, it starts to fall by increasing the baryon chemical potential and it apparently vanishes at $\mu_{B}=(1.03-1.15)$ GeV for finite temperatures: The point of apparent vanishing moves to lower baryon chemical potentials by increasing the temperature. At zero temperature, the mass reaches to roughly a fixed value at higher baryon chemical potentials. On the other hand, the decay constant decreases considerably with respect to baryon chemical potential up to roughly $\mu_{B}=0.4$ GeV, but after this point, it starts to increase in terms of the baryon chemical potential at finite temperatures. At $T=0$, the decay constant reaches to a fixed value at higher chemical potentials, as well. Regarding the dependence on the temperature we observe that, at fixed values of baryon chemical potentials, the mass and decay constant remain roughly unchanged up to $T=50$ MeV and $T=70$ MeV respectively, but after these points, the mass starts to fall and the decay constant starts to rise up to a critical temperature $T=155$ MeV, considerably.