Impact of a thermal medium on $D$ mesons and their chiral partners

Abstract

We study $D$ and $D_s$ mesons at finite temperature using an effective field theory based on chiral and heavy-quark spin-flavor symmetries within the imaginary-time formalism. Interactions with the light degrees of freedom are unitarized via a Bethe-Salpeter approach, and the $D$ and $D_s$ self-energies are calculated self-consistently. We generate dynamically the $D_0^{\ast }(2300)$ and $D_s(2317)$ states, and study their possible identification as the chiral partners of the $D$ and $D_s$ ground states, respectively. We show the evolution of their masses and decay widths as functions of temperature, and provide an analysis of the chiral-symmetry restoration in the heavy-flavor sector below the transition temperature. In particular, we analyse the very special case of the $D$-meson, for which the chiral partner is associated to the double-pole structure of the $D_0^{\ast }(2300)$.

15 pages, 3 figures. v2: Corrected self-consistent calculation due to missing numerical factor. Conclusions remain unchanged. New references and discussion on validity of temperature range. Results on figure 3 provided as ancillary data. Version accepted by Physics Letters B journal