Spectral functions for D¯ and D¯0* mesons in nuclear matter with partial restoration of chiral symmetry

Abstract

We investigate the in-medium masses of aD (0 − ) meson and aD * 0 (0 + ) meson and spectral functions forD andD * 0 meson channels in nuclear matter. These mesons are introduced as chiral partner in the chiral symmetry broken vacuum, hence they are useful to explore the partial restoration of the broken chiral symmetry in nuclear matter. We consider the linear sigma model to describe the chiral symmetry breaking. Our study shows that the loop corrections toD andD * 0 meson masses provide a smaller mass splitting at finite density than that in vacuum, whose result indicates a tendency of the restoration of the chiral symmetry. We investigate also the spectral function forD * 0 meson channel, and find three peaks. The first peak which corresponds to the resonance ofD * 0 meson is broadened by collisions with nucleons in medium, and the peak position shifts to lower mass due to the partial restoration of chiral symmetry as the density increases. The second peak is identified as a threshold enhancement which shows a remarkable enhancement as the density increase. The third peak is Landau damping. The obtained properties ofD andD * 0 mesons in nuclear matter will provide useful information for experiments.

Effect of Partial Chiral Symmetry Restoration in Nuclear Matter to Charmed Meson Masses Based on a Chiral Partner Structure

“…[10]. The results show that the spectral functions are also modified by the effect of partial chiral symmetry restoration.…”

Nature of the D0* meson in Dπ scattering with chiral symmetry

“…To include the chiral partner structure of charmed mesons, we employ the effective Lagrangian based on the linear representation of chiral symmetry [10][11][12][13]. We first introduce the heavy-light meson fields H L,R ∼ Qq L,R , which transform as…”

“…where D = (D 0 , D + ), D † = (D 0 , D − ) t and we have adopted the relativistic notation as in Ref. [13] with m being the chiral invariant mass of the charmed mesons. The first line of Eq.…”

“…We however note that the self-energy should include not only the simple Dπ loop, as was done in Ref. [13], but also the crossed diagrams, in order to satisfy the chiral low-energy theorem.…”

The Change of Spectral Function for Excited D Meson with Partial Restoration of Chiral Symmetry in Nuclear Matter

“…[2]. In this reference, we studied masses ofD (0 − ) meson andD * 0 (0 + ) meson, and spectral function forD * 0 meson in nuclear matter.D mesons are composed of an anti-charm quark and a light quark, so that 1/m c (m c is mass of a charm quark) expansion is applicable and we can construct a concise effective field theory of them [3].…”