Narrow Results

We calculate the decay widths of the charmonium states, J/ψ, ψ(3686) and ψ(3770), to pairs, as well as the decay width of D* → Dπ, in isospin asymmetric strange hadronic matter, using a field theoretical model for composite hadrons with quark constituents. For this purpose, we use the quark–antiquark pair creation term of the free Dirac Hamiltonian written in terms of the constituent quark field operators, and use explicit charmonium, D, , D* and π states to evaluate the matrix elements for the charmonium as well as D* decay amplitudes. The medium modifications of the partial decay widths of charmonium to pair, arising from the mass modifications of the and the charmonium states calculated in a chiral effective model, are also included. The results of the present investigations are then compared with the decay widths computed earlier, in a model using light quark pair creation in ³P₀ state. As in ³P₀ model, the decay amplitude in the present model is multiplied with a strength parameter for the light quark pair creation, which is fitted from the observed vacuum decay width. The effects of the isospin asymmetry, the strangeness fraction of the hadronic matter on the masses of the charmonium states and mesons and hence on the decay widths, have also been studied. The isospin asymmetry effect is observed to be dominant for high densities, leading to appreciable difference in the decay channels of the charmonium to D⁺ D^- and pairs. The decay width of D* → Dπ in the hadronic matter has also been calculated within the composite quark model in the present work, accounting for the medium modifications of the D and D* masses. The density modifications of the charmonium states and D(D*) mesons, which are observed to be appreciable at high densities, will be of relevance in the compressed baryonic matter (CBM) experiments at the future facility of FAIR, GSI, where charmed hadrons will be produced by annihilation of antiprotons on nuclei. The interactions of the charmonium states and D(D*) with the nuclear medium could lead to the possibility of the formation of exotic bound states of the nuclei with the (excited) charmonium states as well as with D(D*) mesons.

The mass modifications of the open charm ($D$ and $D^{\ast }$) mesons, and their effects on the decay widths $D^{\ast }\to D\pi$ as well as of the charmonium state, $\mathrm{\Psi }(3770)$ to open charm mesons ($\mathrm{\Psi }(3770)\to D\bar{D}$), are investigated in the presence of strong magnetic fields. These are studied accounting for the mixing of the pseudoscalar ($P$) and vector ($V$) mesons ($D-D^{\ast }$, ${\eta }_c^{\prime }-\mathrm{\Psi }(3770)$ mixings), with the mixing parameter, $g_{PV}$ of a phenomenological three-point ($PV\gamma$) vertex interaction determined from the observed radiative decay width of $V\to P\gamma$. For charged $D-D^{\ast }$ mixing, this parameter is dependent on the magnetic field, because of the Landau level contributions to the vacuum masses of these mesons. The masses of the charged $D$ and $D^{\ast }$ mesons modified due to $PV$ mixing, in addition, have contributions from the lowest Landau levels in the presence of a strong magnetic field. The effects of the magnetic field on the decay widths are studied using a field theoretical model of composite hadrons with quark (and antiquark) constituents. 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 charmonium state $\mathrm{\Psi }(3770)$, the open charm ($D$, $\bar{D}$, $D^{\ast }$) mesons and the pion states in terms of the constituent quark fields. The parameter for the charged $D-D^{\ast }$ mixing is observed to increase appreciably with increase in the magnetic field. This leads to dominant modifications to their masses, and hence the decay widths of charged $D^{\ast }\to D\pi$ as well as $\mathrm{\Psi }(3770)\to D^{+}{D}^{-}$ at large values of the 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 $D^{\ast }$) mesons as well as of the charmonium states resulting from noncentral ultra-relativistic heavy ion collision experiments.

In this paper, we investigate the masses of the pseudoscalar ($D$($D^0$, $D^{+}$), $\bar{D}$($\overline{D^0}$, $D^{-}$) and vector open charm mesons ($D^{\ast }$($D^{\ast 0}$, $D^{\ast +}$), ${\bar{D}}^{\ast }$(${\bar{D}}^{\ast 0}$, $D^{\ast -}$) as well as the pseudoscalar (${\eta }_c(1S)$, ${\eta }_c(2S)$) and the vector charmonium states ($J∕\psi$, $\psi (2S)$, $\psi (1D)$) in the asymmetric hot strange hadronic medium in the presence of strong magnetic fields. In the magnetized medium, the mass modification of open charm mesons due to their interactions with baryons and the scalar fields ($\sigma$, $\zeta$, and $\delta$) is investigated in a chiral effective model. Moreover, the charged pseudoscalar meson ($D^{\pm }$), as well as the longitudinal component of charged vector meson ($D^{\ast \pm \parallel }$), experience additional positive mass modifications in the magnetic field due to Landau quantization. The effect of the modification of gluon condensates simulated by the medium change of dilaton field $\chi$ on the masses of the charmonia is also calculated in the chiral effective model. The contribution of masses of light quarks is also considered in the modification of gluon condensates. At high temperatures, the magnetically induced modifications of scalar fields significantly reduce the in-medium masses of mesons. The effects of magnetically induced spin mixing between the pseudoscalar and the corresponding vector mesons are incorporated in our study through a phenomenological effective Lagrangian interaction. The spin mixing result in a positive mass shift for the longitudinal component of the vector mesons and a negative mass shift for the pseudoscalar mesons in the presence of the magnetic field. From the obtained in-medium masses of charmonia and open charm mesons, we have also calculated the partial decay widths of $\psi (1D)$ to $D\bar{D}$, using a light quark pair creation model, namely, the ${}^3{P}_0$ model.