Study of semileptonic decays of $B$ mesons to charmed baryons

Using data collected by the CLEO II detector at a center-of-mass energy on or near the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance, we have determined the 90% confidence level upper limit $\mathcal{B}(\overline{B}\to {\Lambda }_c^{+}{e}^{-}X)/\mathcal{B}(\overline{B}\to ({\Lambda }_c^{+}\hspace{0.5em}or\hspace{0.5em}{\overline{\Lambda }}_c^{-}\left)X\right)<0.05\mathrm{}$ for electrons with momentum above $0.6\mathrm{GeV}/c.\mathrm{}$ We have also obtained the limit $\mathcal{B}{(B}^{-}\to {\Lambda }_c^{+}\overline{p}{e}^{-}{\overline{\nu }}_e)/\mathcal{B}(\overline{B}\to {\Lambda }_c^{+}\overline{p}X)<\mathrm{}0.04\mathrm{}$ at the 90% confidence level and measured the ratio $\mathcal{B}(\overline{B}\to {\Lambda }_c^{+}\overline{p}X)/\mathcal{B}(\overline{B}\to ({\Lambda }_c^{+}\hspace{0.5em}or\hspace{0.5em}{\overline{\Lambda }}_c^{-}\left)X\right)=0.57\mathrm{}\pm 0.05\pm \mathrm{0.05.}$