6533b7d4fe1ef96bd1261eca

RESEARCH PRODUCT

Semileptonic decays ofBcmesons into charmonium states in a relativistic quark model

subject

description

We use the framework of a relativistic constituent quark model to study the semileptonic transitions of the ${B}_{c}$ meson into $(\overline{c}c)$ charmonium states where $(\overline{c}c)={\ensuremath{\eta}}_{c}(^{1}S_{0})$, $J/\ensuremath{\psi}(^{3}S_{1})$, ${\ensuremath{\chi}}_{c0}(^{3}P_{0})$, ${\ensuremath{\chi}}_{c1}(^{3}P_{1})$, ${h}_{c}(^{1}P_{1})$, ${\ensuremath{\chi}}_{c2}(^{3}P_{2})$, $\ensuremath{\psi}(^{3}D_{2})$. We compute the ${q}^{2}$ dependence of all relevant form factors and give predictions for their semileptonic ${B}_{c}$ decay modes including also their $\ensuremath{\tau}$ modes. We derive a formula for the polar angle distribution of the charged lepton in the $(l{\ensuremath{\nu}}_{l})$-c.m. frame and compute the partial helicity rates that multiply the angular factors in the decay distribution. For the discovery channel ${B}_{c}\ensuremath{\rightarrow}J/\ensuremath{\psi}(\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})l\ensuremath{\nu}$ we compute the transverse/longitudinal composition of the $J/\ensuremath{\psi}$ which can be determined by an angular analysis of the decay $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$. We compare our results with the results of other calculations.