Λ c semileptonic decays in a quark model

Hadronic form factors for semileptonic decay of the ${\mathrm{\ensuremath{\Lambda}}}_{c}$ are calculated in a nonrelativistic quark model. The full quark model wave functions are employed to numerically calculate the form factors to all relevant orders in ($1/{m}_{c}$, $1/{m}_{s}$). The form factors obtained satisfy relationships expected from the heavy quark effective theory (HQET). The differential decay rates and branching fractions are calculated for transitions to the ground state and a number of excited states of $\mathrm{\ensuremath{\Lambda}}$. The branching fraction of the semileptonic decay width to the total width of ${\mathrm{\ensuremath{\Lambda}}}_{c}$ has been calculated and compared with other theoretical estimates and experimental results. The branching fractions for ${\mathrm{\ensuremath{\Lambda}}}_{c}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}^{*}{l}^{+}{\ensuremath{\nu}}_{l}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Sigma}}\ensuremath{\pi}{l}^{+}{\ensuremath{\nu}}_{l}$ and ${\mathrm{\ensuremath{\Lambda}}}_{c}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}^{*}{l}^{+}{\ensuremath{\nu}}_{l}\ensuremath{\rightarrow}N\overline{K}{l}^{+}{\ensuremath{\nu}}_{l}$ are also calculated. Apart from decays to the ground state $\mathrm{\ensuremath{\Lambda}}(1115)$, it is found that decays through the $\mathrm{\ensuremath{\Lambda}}(1405)$ provide a significant portion of the branching fraction ${\mathrm{\ensuremath{\Lambda}}}_{c}\ensuremath{\rightarrow}{X}_{s}l{\ensuremath{\nu}}_{l}$. A new estimate for $f=B({\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}{l}^{+}{\ensuremath{\nu}}_{l})/B({\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}{X}_{s}{l}^{+}{\ensuremath{\nu}}_{l})$ is obtained.