Anatomy of $\Lambda_c^+$ semileptonic decays

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.