Measurement of the absolute branching fraction for $\Lambda^+_{c}\to \Lambda e^+\nu_e$

TL;DR

This paper presents the first absolute measurement of the branching fraction for the decay b1^+_c b1 e^+ b1_e u_e, using data from BESIII, significantly improving the precision and providing a key benchmark for theoretical models.

Contribution

It reports the first absolute measurement of b1^+_c b1 e^+ b1_e u_e branching fraction with enhanced precision, serving as a benchmark for testing theoretical models.

Findings

Branching fraction measured as (3.63 b1 0.38 b1 0.20)%

More than twofold improvement in measurement precision

Provides a stringent test for theoretical models of b1^+_c semileptonic decays

Abstract

We report the first absolute measurement of the branching fraction of $\Lambda^+_{c}\rightarrow \Lambda e^+\nu_e$. This measurement is based on 567 pb$^{-1}$ of $e^+e^-$ annihilation data produced at $\sqrt{s}=4.599$ GeV, which is just above the $\Lambda^+_c\bar{\Lambda}^-_c$ threshold. The data were collected with the BESIII detector at the BEPCII storage rings. The branching fraction is determined to be $\mathcal B({\Lambda^+_c\rightarrow \Lambda e^+\nu_e})=(3.63\pm0.38({\rm stat})\pm0.20({\rm syst}))\%$, representing a more than twofold improvement in precision upon previously published results. As the branching fraction for $\Lambda^+_{c}\rightarrow \Lambda e^+\nu_e$ is the benchmark for those of other $\Lambda^+_c$ semileptonic channels, our result provides a unique test of different theoretical models, which is the most stringent to date.