Anatomy of $\Lambda_c^+$ semileptonic decays

TL;DR

This paper systematically studies the semileptonic decays of the $\Lambda_c^+$ baryon using the homogeneous bag model and lattice QCD, providing predictions for decay observables and exploring potential new physics effects.

Contribution

It offers the first comprehensive analysis of $\Lambda_c^+$ semileptonic decays with detailed predictions from two theoretical frameworks and investigates time-reversal asymmetries for new physics signals.

Findings

Predicted branching fractions and polarization asymmetries for $\Lambda_c^+$ decays.

Lattice QCD results for decay asymmetries with high precision.

Consistency of results with current experimental data and predictions accessible to BESIII and Belle II.

Abstract

We present a systematic study of $\Lambda_c^+ \to {\cal B}_q \ell^+ \nu_\ell $ with ${\cal B}_q = (\Lambda, n)$ and $\ell =( e, \mu)$, examining all the possible decay observables based on the homogeneous bag model (HBM) and lattice QCD (LQCD). With the HBM, we find that the branching fractions and polarization asymmetries of the daughter baryon $\Lambda$ are ${\cal B}(\Lambda_c^+ \to \Lambda e^+ \nu_e, \Lambda \mu^+ \nu_\mu, n \ell ^+ \nu_\ell ) = (3.78 \pm 0.25, 3.67\pm 0.23, 0.40\pm 0.04 )\%$ and $\alpha_\Lambda (\Lambda_c^+ \to \Lambda e^+ \nu_e,\Lambda\mu^+ \nu_\mu ) =(-82.6,-82.3)\%$, respectively. From the LQCD, we obtain that $\alpha_{\Lambda}(\Lambda_c^+ \to \Lambda e^+ \nu_e, \mu^+ \nu_\mu ) = (-87.4\pm 1.0,-87.2\pm 1.0)\%$. We also explore the time-reversal asymmetries due to new physics beyond the standard model. All our results are consistent with the current experimental data, while some of them are accessible to the experiments at BESIII and Belle II.