Revisiting semileptonic $B^-\to p\bar{p} \ell^- \barν_{\ell}$ decays

Abstract: We systematically revisit the baryonic four-body semileptonic decays of $B^- \to {\bf B}\bar{\bf B}&#39;\ell^- \bar{\nu}<em>{\ell}$ by the perturbative QCD counting rules with ${\bf B}$ representing octet baryons and $\ell=e,\mu$. We study the transition form factors of $B^- \to {\bf B} \bar{\bf B}&#39;$ in the limit of $(p</em>{\bf B}+p_{\bar{\bf B}&#39;})² \to \infty $ with the three-body $\bar{B}\to {\bf B}\bar{\bf B}&#39; M$ and $$B^- \to p\bar{p} \mu^- \bar{\nu}<em>{\mu}$$ data along with $SU(3)_f$ flavor symmetry. We calculate the decay branching ratios and angular asymmetries as well as the differential decay branching fractions of $$B^- \to p \bar{p} \ell^- \bar{\nu}</em>{\ell}$$. In particular, we find that our new result of $${\cal B}( B^- \to p \bar{p} \ell^- \bar{\nu}<em>{\ell})=(5.21\pm0.34)\times 10<sup>{-6}$$, which is about one order of magnitude lower than the previous theoretical prediction of $(10.4\pm2.9)\times 10<sup>{-5}$, agrees well with both experimental measurements of $$(5.8^{+2.6}</em>{-2.3})\times 10<sup>{-6}$$ and $(5.3\pm0.4)\times 10<sup>{-6}$ by the Belle and LHCb Collaborations, respectively. We also evaluate the branching ratios and angular asymmetries in other channels of $$B^- \to {\bf B}\bar{\bf B}\ell^- \bar{\nu}_{\ell}$$, which can be tested by the ongoing experiments at LHCb and BelleII.