Effect of in-medium spectral density of $D$ and $D^{\ast }$ mesons on the $J\mathrm{/}\psi$ dissociation in hadronic matter

The one-loop self-energy of the $D$ and $D^{\ast }$ mesons in a hot hadronic medium is evaluated using the real time formalism of thermal field theory. The interaction of the heavy open-charm mesons with the thermalized constituents $(\pi ,K,\eta )$ of the hadronic matter is treated in the covariant formalism of heavy meson chiral perturbation theory. The imaginary parts are extracted from the discontinuities of the self-energy function across the unitary and the Landau cuts. The non-zero contribution from the latter to the spectral density of $D$ and $D^{\ast }$ mesons opens a number of subthreshold decay channels of the $J\mathrm{/}\psi$ leading to a significant increase in the dissociation width in hadronic matter.