Light-cone Sum Rule Analysis of Semileptonic Decays ${\Lambda }_b^0\to {\Lambda }_c^{+}{\ell }^{-}{\overline{\nu }}_{\ell }$

Abstract

In this work, we analyze the semileptonic decay processes of ${\Lambda }_b\to {\Lambda }_c$ in the light-cone sum rule approach. In order to calculate the form factors of the ${\Lambda }_b$ baryon transition matrix element, we use the light-cone distribution amplitudes of ${\Lambda }_b$ obtained from the QCD sum rule in the heavy quark effective field theory framework. With the calculation of the six form factors of the ${\Lambda }_b\to {\Lambda }_c$ transition matrix element, the differential decay widths of ${\Lambda }_b^0\to {\Lambda }_c^{+}{\ell }^{-}{\overline{\nu }}_{\ell }(\ell =e,\mu ,\tau )$ and their absolute branching fractions are obtained. Additionally, the ratio of $R({\Lambda }_c^{+})\equiv \mathcal{B}r({\Lambda }_b^0\to {\Lambda }_c^{+}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}r({\Lambda }_b^0\to {\Lambda }_c^{+}{\mu }^{-}{\overline{\nu }}_{\mu })$ is also obtained in this work. Our results are in accord with the newest experimental result and other theoretical calculations and predictions.

Comments: 15 pages, 2 figures, 6 tables