Open charm and charmonium states in strong magnetic fields.

The mass modifications of the open charm ($D$ and $D^*$) mesons, and their effects on the decay widths $D^*\rightarrow D\pi$ as well as of the charmonium state, $\Psi(3770)$ to open charm mesons ($\Psi(3770)\rightarrow D\bar D$), are investigated in the presence of strong magnetic fields. These are studied accounting for the mixing of the psuedoscalar and vector mesons ($D-D^*$, $\eta_c'-\Psi(3770)$ mixings), which is observed to lead to a drop (increase) in the mass of the pseudoscalar (longitdinal component of the vector) meson. The charged $D$ and $D^*$ mesons, in addition, have the Landau level contributions in the presence of the magnetic field. The effects of the magnetic field on the decay widths are studied using a field theoretic model of composite hadrons with quark (and antiquark) consittuents. The matrix elements for these decays are evaluated using the light quark--antiquark pair creation term of the free Dirac Hamiltonian for the constituent quark field, with explicit constructions for the the charmonium state $\Psi(3770)$, the open charm ($D$, $\bar D$, $D^*$) mesons and the pion states in terms of the constituent quark fields. The medium modifications of these decay widths arise due to the mass modifications of the open charm mesons as well as of the charmonium state, $\Psi(3770)$, which have dominant contributions due to the $D-D^*$, $\Psi(3770)-\eta_c'$ mixings in the presence of a magnetic field. The modifications of the masses and decay widths of the open and hidden charm mesons in the presence of strong magnetic fields should have observable consequences on the production of the open charm ($D$ and $D^*$) mesons as well as of the charmonium states resulting from non-central ultrarelativistic heavy ion collision experiments.