Chiral-partner D mesons in a heat bath within QCD sum rules

TL;DR

This paper uses QCD sum rules to study how the spectral properties of chiral partner D mesons change with temperature, revealing mass shifts and decay constant modifications that suggest partial chiral restoration in a hot medium.

Contribution

It provides the first analysis of temperature-dependent spectral properties of D mesons as chiral partners using QCD sum rules, including decay constants and implications for chiral symmetry restoration.

Findings

Scalar D meson mass decreases with temperature

Pseudo-scalar D meson properties are largely unaffected by temperature

Decay constants of scalar D mesons decrease, indicating partial chiral restoration

Abstract

Utilizing QCD sum rules, we extract the temperature dependences of the spectral properties of the pseudo-scalar and scalar D mesons regarded as chiral partners. Besides the masses also decay constants are analyzed as the D meson yields in heavy-ion collisions may be sensitive to their altered decay properties in an ambient strongly interacting medium. Our findings are ($i$) a decreasing scalar D meson mass for growing temperatures while its pseudo-scalar partner meson seems hardly affected, which is in qualitative agreement with hadronic model calculations; ($ii$) inferring an equally weak temperature dependence of the pseudo-scalar D meson decay properties the decreasing residua and decay constants of the scalar particle point towards partial chiral restoration. As a bonus of our analysis in the pseudo-scalar sector we determine the pseudo-scalar decay constant at vanishing temperature. Due to the connection to particular leptonic branching fractions this decay constant is of great interest allowing for the determination of the off-diagonal CKM matrix element $|V_{cd}|$ at zero temperature.