This work presents the search for the semileptonic baryonic B decay $B^- \rightarrow \Lambda_c^+ \bar{ p} \ell^- \bar{ \nu}_{ \ell}$. The used data comprises the complete BABAR data set of $470 \cdot 10^{ 6}$ $B\bar{ B}$ events, collected at the SLAC National Accelerator Laboratory. Using a pole-model decay simulation, we obtain upper limits with $90\%$ confidence level of $B(B^- \rightarrow \Lambda_c^+ \bar{ p} e^- \bar{ \nu}_{ e})\cdot \frac{ B(\Lambda_c^+ \rightarrow p K^- \pi^+)}{ 5\%} < 1.2 \times 10^{ -4}$, $B(B^- \rightarrow \Lambda_c^+ \bar{ p} \mu^- \bar{ \nu}_{ \mu})\cdot \frac{ B(\Lambda_c^+ \rightarrow p K^- \pi^+)}{ 5\%} < 2.5 \times 10^{ -4}$, $B(B^- \rightarrow \Lambda_c^+ \bar{ p} \ell^- \bar{ \nu}_{ \ell})\cdot \frac{ B(\Lambda_c^+ \rightarrow p K^- \pi^+)}{ 5\%} < 1.0 \times 10^{ -4}$. These results are in slight tension with predictions based on the measurement of $B^- \rightarrow \bar{ p} p \ell^- \bar{ \nu}_{ \ell}$ and $B^- \rightarrow \Lambda_c^+ \bar{ p} \pi^-$.
Categories: hep-ex