Study of the Semileptonic Decay $\Lambda_c^+\rightarrow \Lambda e^+\nu_e$

TL;DR

This paper reports the most precise measurement to date of the branching fraction for the semileptonic decay $\Lambda_c^+ ightarrow \Lambda e^+ u_e$, compares the decay dynamics with lattice QCD predictions, and determines the CKM matrix element |V_{cs}|.

Contribution

It provides the first direct comparison of differential decay rates and form factors with lattice QCD calculations for this decay.

Findings

Branching fraction measured as (3.56±0.11±0.07)%

First comparison of decay dynamics with lattice QCD

Determination of |V_{cs}|=0.936±0.017±0.024±0.007

Abstract

The measurement of the Cabibbo-favored semileptonic decay $\Lambda_c^+\rightarrow \Lambda e^+\nu_e$ is reported using a $4.5~\mathrm{fb}^{-1}$ data sample of $e^+e^-$ annihilations collected at center-of-mass energies ranging from 4.600~GeV to 4.699~GeV with the BESIII detector at the BEPCII collider. The branching fraction of the decay is measured to be $\mathcal{B}(\Lambda_c^+\rightarrow \Lambda e^+\nu_e)=(3.56\pm0.11_{\rm stat.}\pm0.07_{\rm syst.})\%$, which is the most precise measurement to date. Furthermore, we perform an investigation of the internal dynamics in $\Lambda_c^+\rightarrow \Lambda e^+\nu_e$. We provide the first direct comparisons of the differential decay rate and form factors with those predicted from lattice quantum chromodynamics (LQCD) calculations. Combining the measured branching fraction with a $q^2$-integrated rate predicted by LQCD, we determine $|V_{cs}|=0.936\pm0.017_{\mathcal{B}}\pm0.024_{\rm LQCD}\pm0.007_{\tau_{\Lambda_c}}$.