Open Heavy flavour mesons in hot asymmetric strange hadronic matter -- a QCD sum rule approach

Abstract: The in-medium masses of the pseudoscalar open charm ($D$, $\bar D$, $D_s$ and $\bar {D_s}$) and open bottom ($B$, $\bar B$, $B_s$ and $\bar {B_s}$) mesons in hot asymmetric strange hadronic matter are studied within a QCD sum rule approach. These are computed using the medium modifications of the light quark condensates ($\langle{\bar{q_i}}{q_i}\rangle$, with $(q_i,i=1,2,3)\equiv(u,d,s)$), the scalar gluon condensate, $\left\langle \frac{\alpha_{s}}{\pi} G^a_{\mu\nu} {G^a}^{\mu\nu} \right\rangle$, the twist-2 tensorial gluon operator, $\left\langle \frac{\alpha_{s}}{\pi} \Big (G^a_{\mu\sigma} {{G^a}_\nu}^{\sigma} u^\mu u^\nu -\frac{1}{4} G^a_{\mu\sigma} {G^a}^{\mu \sigma}\Big) \right\rangle$ (where $u^\mu$ is the 4-velocity of the medium) and other operators in the operator product expansion upto mass dimension 5. Within a chiral SU(3) model, the quark condensates are obtained from the medium modifications of the non-strange and strange scalar-isoscalar fields ($\sigma$ and $\zeta$), and the scalar-isovector field, $\delta$, whereas, the gluon (scalar and twist-2) condensates are computed from the in-medium value of the dilaton field, $\chi$, which is incorporated within the chiral model to mimic the broken scale invariance of QCD. The mixed quark-gluon condensate $\langle \bar {q_i} g_s \sigma . G q_i \rangle$ is calculated from the in-medium quark condensate $\langle \bar {q_i} q_i \rangle$. The splittings of the masses of the $D-\bar D$ ($B-\bar B)$, as well as $D_s-\bar {D_s} (B_s-\bar {B_s})$ in the hadronic medium are due to the odd part of the spectral function. The effects of density, isospin asymmetry, strangeness and temperature on the masses of the open charm and open bottom mesons are observed to be appreciable.