Upsilon decay widths in magnetized asymmetric nuclear matter

Abstract

The in-medium partial decay widths of [Formula: see text] in magnetized asymmetric nuclear matter are studied using a field theoretic model for composite hadrons with quark (and antiquark) constituents. [Formula: see text] is the lowest bottomonium state which can decay to [Formula: see text] in vacuum. The medium modifications of the decay widths of [Formula: see text] to [Formula: see text] pair in magnetized matter arise due to the mass modifications of the decaying [Formula: see text] as well as of the produced [Formula: see text] and [Formula: see text] mesons. The in-medium masses of the open bottom meson in magnetized nuclear matter are computed from their interactions with the nucleons and the scalar mesons within a chiral effective model. The mass modification of the [Formula: see text] arises due to the medium modification of a scalar dilaton field, which is introduced in the model to simulate the gluon condensates of QCD. The effects of the anomalous magnetic moments for the proton and neutron are taken into consideration in the present investigation. The presence of the external magnetic field is observed to lead to different mass modifications within the [Formula: see text] as well as the [Formula: see text] doublets, even in isospin symmetric nuclear matter. This is due to the difference in the interactions of the proton and the neutron to the electromagnetic field. The charged [Formula: see text] mesons have additional contributions from the Landau energy levels, leading to positive shifts in their masses in the presence of a magnetic field. In the presence of an external magnetic field, there are contributions to the masses of the B, [Formula: see text] mesons and [Formula: see text] state (longitudinal component) due to the pseudoscalar meson–vector meson (PV) mixing ([Formula: see text], [Formula: see text] and [Formula: see text] mixings), which are also considered in this study. The PV mixing effects are observed to be the dominant contributions to the mass shifts of these mesons, which lead to appreciable modifications in the decay widths of [Formula: see text] to the neutral ([Formula: see text]) and the charged ([Formula: see text]) pairs in the presence of a magnetic field. These should have observable consequence in the production of open bottom mesons and bottomonium states at LHC and RHIC, where huge magnetic fields are produced in ultra-relativistic peripheral heavy-ion collisions.