Λc semileptonic decays in a quark model

Hadronic form factors for semileptonic decay of the ${\mathrm{\Lambda }}_c$ 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 $\mathrm{\Lambda }$. The branching fraction of the semileptonic decay width to the total width of ${\mathrm{\Lambda }}_c$ has been calculated and compared with other theoretical estimates and experimental results. The branching fractions for ${\mathrm{\Lambda }}_c\to {\mathrm{\Lambda }}^{*}{l}^{+}{\nu }_l\to \mathrm{\Sigma }\pi l^{+}{\nu }_l$ and ${\mathrm{\Lambda }}_c\to {\mathrm{\Lambda }}^{*}{l}^{+}{\nu }_l\to N\overline{K}{l}^{+}{\nu }_l$ are also calculated. Apart from decays to the ground state $\mathrm{\Lambda }(1115)$, it is found that decays through the $\mathrm{\Lambda }(1405)$ provide a significant portion of the branching fraction ${\mathrm{\Lambda }}_c\to X_{s}l{\nu }_l$. A new estimate for $f=B({\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{l}^{+}{\nu }_l)/B({\mathrm{\Lambda }}_c^{+}\to X_s{l}^{+}{\nu }_l)$ is obtained.