Screening Masses for Scalar and Pseudoscalar Mesons and their Diquark Partners: Insights from the Contact Interaction Model

TL;DR

This paper calculates the screening masses of scalar and pseudoscalar mesons and diquarks across a range of temperatures using a contact interaction model, providing insights into chiral symmetry restoration and hadron properties at high temperatures.

Contribution

It extends the Dyson-Schwinger equation framework to compute screening masses for a broad set of mesons and diquarks up to 500 MeV, highlighting degeneracy and symmetry restoration phenomena.

Findings

Screening masses of parity partners become degenerate above a characteristic temperature.

Diquark screening masses converge at high temperatures, implying equal contributions to baryon masses.

Results are consistent with other approaches, supporting the model's validity.

Abstract

In this study, we calculate the screening masses of forty spin-zero meson and diquark states composed of light, heavy and heavy-light quarks, within a symmetry-preserving framework based on Dyson-Schwinger equations and a vector $\times$ vector contact interaction. This effective interaction reproduces hadron static properties at $T=0$ MeV that are in close agreement with experimental data and results from more sophisticated interaction kernels. Our analysis reveals that, at temperatures above the critical temperature, the dressed quark masses of the lightest mesons converge toward their respective current quark masses. Our work extends this study up to $T=500$ MeV. Furthermore, we demonstrate that the screening masses of meson parity partners become degenerate above a characteristic temperature, a phenomenon that is likewise reflected in the thermal evolution of their associated Bethe-Salpeter amplitudes (BSAs), providing robust evidence for chiral symmetry restoration. A similar trend is observed for scalar and pseudoscalar diquarks, whose screening masses also converge at high temperatures. As a consequence, these diquarks shall contribute equally to the baryon screening masses in the high-temperature regime. Wherever results from other approaches are available, we perform direct comparisons and observe consistency with our findings.