We calculate the in-medium masses of the bottomonium states (Υ(1S), Υ(2S), Υ(3S) and Υ(4S)) in isospin asymmetric strange hadronic matter at finite temperatures. The medium modifications of the masses arise due to the interaction of these heavy quarkonium states with the gluon condensates of QCD. The gluon condensates in the hot hadronic matter are computed from the medium modification of a scalar dilaton field within a chiral SU(3) model, introduced in the hadronic model to incorporate the broken scale invariance of QCD. There is seen to be drop in the masses of the bottomonium states and mass shifts are observed to be quite considerable at high densities for the excited states. The effects of density, isospin asymmetry, strangeness as well as temperature of the medium on the masses of the Υ-states are investigated. The effects of the isospin asymmetry as well as strangeness fraction of the medium are seen to be appreciable at high densities and small temperatures. The density effects are the most dominant medium effects which should have observable consequences in the compressed baryonic matter (CBM) in the heavy ion collision experiments in the future facility at FAIR, GSI. The study of the Υ states will however require access to energies higher than the energy regime planned at CBM experiment. The density effects on the bottomonium masses should also show up in the dilepton spectra at the SPS energies, especially for the excited states for which the mass drop is observed to quite appreciable.

The in-medium masses and optical potentials of B andB mesons are studied in an isospin asymmetric, strange, hot and dense hadronic environment using a chiral effective model. The chiral SU (3) model originally designed for the light quark sector, is generalized to include the heavy quark sector (c and b) to derive the interactions of the B andB mesons with the light hadrons. Due to large mass of bottom quark, we use only the empirical form of these interactions for the desired purpose, while treating the bottom degrees of freedom to be frozen in the medium.Hence, all medium effects are due to the in-medium interaction of the light quark content of these open-bottom mesons. Both B andB mesons are found to experience net attractive interactions in the medium, leading to lowering of their masses in the medium. The mass degeneracy of particles and antiparticles, (B + , B − ) as well as (B 0 ,B 0 ), is observed to be broken in the medium, due to equal and opposite contributions from a vectorial Weinberg-Tomozawa interaction term. Addition of hyperons to the medium lowers further the in-medium mass for each of these four mesons, while a non-zero isospin asymmetry is observed to break the approximate mass degeneracy of each pair of isospin doublets. These medium effects are found to be strongly density dependent, and bear a considerably weaker temperature dependence. The results obtained in the present investigation are compared to predictions from the quark-meson coupling model, heavy meson effective theory, and the QCD Sum Rule approach.

The in-medium behavior of bottom-strange pseudoscalar mesons in hot, isospin asymmetric and dense hadronic environment is studied using a chiral effective model. The same was recently generalized to the heavy quark sector and employed to study the behavior of open-charm and open-bottom mesons. The heavy quark (anti-quark) is treated as frozen and all medium modifications of these bottom-strange mesons are due to their strange anti-quark (quark) content. We observe a pronounced dependence of their medium mass on baryonic density and strangeness content of the medium. Certain aspects of these in-medium interactions are similar to those observed for the strange-charmed mesons in a preceding investigation, such as the lifting of mass-degeneracy of $B_S^0$ and ${\bar B}_S^0$ mesons in hyperonic matter, while the same is respected in vacuum as well as in nuclear matter. In general, however, there is a remarkable distinction between the two species, even though the formalism predicts a completely analogous in-medium interaction Lagrangian density. We discuss in detail the reason for different in-medium behavior of these bottom-strange mesons as compared to charmed-strange mesons, despite the dynamics of the heavy quark being treated as frozen in both cases.Comment: 16 pages, 2 figure

The in-medium properties of D S mesons are investigated within the framework of an effective hadronic model, which is a generalization of a chiral SU(3) model, to SU(4), in order to study the interactions of the charmed hadrons. In the present work, the D s mesons are observed to experience net attractive interactions in a dense hadronic medium, hence reducing the masses of the D + S and D − S mesons from the vacuum values. While this conclusion holds in both nuclear and hyperonic media, the magnitude of the mass drop is observed to intensify with the inclusion of strangeness in the medium. Additionally, in hyperonic medium, the mass degeneracy of the D S mesons is observed to be broken, due to opposite signs of the Weinberg-Tomozawa interaction term in the Lagrangian density. Along with the magnitude of the mass drops, the mass splitting between D + S and D − S mesons is also observed to grow with an increase in baryonic density and strangeness content of the medium. However, all medium effects analyzed are found to be weakly dependent on isospin asymmetry and temperature. We discuss the possible implications emanating from this analysis, which are all expected to make a significant difference to observables in heavy ion collision experiments, especially the upcoming Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR), GSI, where matter at high baryonic densities is planned to be produced.

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