The QCD scalar susceptibility and thermal scalar resonances in chiral symmetry restoration

TL;DR

This paper demonstrates that the thermal properties of the lightest scalar resonance, the $f_0(500)$, can explain the QCD scalar susceptibility at finite temperature, aligning well with lattice QCD data and experimental results, highlighting the importance of thermal resonances in chiral symmetry restoration.

Contribution

The study shows that the thermal $f_0(500)$ resonance, modeled via Unitarized Chiral Perturbation Theory, accurately describes the QCD scalar susceptibility and its temperature dependence, consistent with lattice and experimental data.

Findings

Good agreement with lattice QCD data for susceptibility and quark condensate mass differences.

Thermal $f_0(500)$ resonance explains chiral symmetry restoration dynamics.

Low-energy constants match $T=0$ phenomenology.

Abstract

Building upon recent results on the role of thermal resonances in chiral symmetry restoration, we show that a description of the QCD scalar susceptibility at finite temperature $T$ saturated by the thermal properties of the lightest scalar resonance, the $f_0(500)$, is compatible both with lattice QCD data at nonzero $T$ and with the $T=0$ light resonance properties coming from experimental data. The thermal $f_0(500)$ is generated within the framework of Unitarized Chiral Perturbation Theory. This method allows us to achieve a good description of lattice QCD results with a reliable pion mass dependence. In particular, we perform direct fits to the chiral susceptibility measured in lattice data at different pion masses and temperatures, obtaining a remarkable agreement for the susceptibility and for mass differences of the light quark condensate. In addition, the fitted low-energy constants are compatible with $T=0$ phenomenology. Our results confirm the role of unitarized approaches and thermal resonances in the dynamics of the QCD transition.