Semileptonic Decays of $\Lambda \to p \ell^{-} \bar{\nu}_{\ell}$ in the Light-Front Dynamics

Abstract

We investigate the exclusive semileptonic decays of $\Lambda \to p \ell^{-} \bar{\nu}_{\ell}~(\ell=e,\mu)$ within the Standard Model using the light-front quark model. The transition form factor behaviors of $\Lambda \to p$ are obtained from the effective treatment of nonvalence contributions in addition to the valence ones in the Drell-Yan-West frame due to the Bethe-Salpeter formalism. Based on these form factors, we obtain that the branching ratios of $\Lambda\to p e^{-} \bar{\nu}_{e}$ and $p \mu^{-} \bar{\nu}_{\mu}$, including nonvalence contributions, are around $8.32\times 10^{-4}$ and $1.31\times 10^{-4}$, which are consistent with the latest measurements from the BESIII Collaboration, respectively. Our results indicate that nonvalence contributions can play a non-negligible role in the semileptonic baryon decays within the light-front framework.