Holographic meson mass splitting in the Nuclear Matter

TL;DR

This paper investigates how the mass spectra of light mesons split in nuclear matter using holographic models, revealing that density differences between protons and neutrons cause specific mass shifts and potential pion condensation.

Contribution

It introduces a holographic approach to analyze meson mass splitting in nuclear matter considering proton-neutron density differences, including the possibility of pion condensation.

Findings

Mass splitting depends on proton-neutron density difference.

Negatively charged pion can become massless, indicating pion condensation.

Heavy quarkonium binding energy weakens with increasing density difference.

Abstract

We study the holographic light meson spectra and their mass splitting in the nuclear medium. In order to describe the nuclear matter, we take into account the thermal charged AdS geometry with two flavor charges, which can be reinterpreted as the number densities of proton and neutron after some field redefinitions. We show that the meson mass splitting occurs when there exists the density difference between proton and neutron. Depending on the flavor charge, the mass of the positively (negatively) charged meson increases (decreases) as the density difference increases, whereas the neutral meson mass is independent of the density difference. In the regime of the large nucleon density with a relatively large number difference between proton and neutron, we find that negatively charged pion becomes massless in the nuclear medium, so the pion condensate can occur. We also investigate the binding energy of a heavy quarkonium in the nuclear medium, in which the binding energy of a heavy quarkonium becomes weaker as the density difference increases.