Measurement of the Absolute Branching Fraction for Λc+→Λe+νe

Le résumé fourni par la source

We report the first measurement of the absolute branching fraction for ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}{e}^{+}{\ensuremath{\nu}}_{e}$. This measurement is based on $567\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ annihilation data produced at $\sqrt{s}=4.599\text{ }\text{ }\mathrm{GeV}$, which is just above the ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}$ threshold. The data were collected with the BESIII detector at the BEPCII storage rings. The branching fraction is determined to be $\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}{e}^{+}{\ensuremath{\nu}}_{e})=[3.63\ifmmode\pm\else\textpm\fi{}0.38(\text{stat})\ifmmode\pm\else\textpm\fi{}0.20(\text{syst})]%$, representing a significant improvement in precision over the current indirect determination. As the branching fraction for ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}{e}^{+}{\ensuremath{\nu}}_{e}$ is the benchmark for those of other ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}$ semileptonic channels, our result provides a unique test of different theoretical models, which is the most stringent to date.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.