Decay rates of $\Lambda_b^0 \to \Lambda_c^+ \ell^- \bar\nu_\ell$ using helicity analysis and phase-moment parametrization

Abstract

Based on the helicity method, formulae for the semileptonic transition of $\Lambda_b^0 \to \Lambda_c^+ \ell^- \bar \nu_\ell$ including lepton mass effects are derived. In order to calculate the form factors of the $\Lambda_b$ baryon transition matrix element, we employ the phase-moment parameterization and perform fits to the Lattice QCD data. With the help of the obtained form factors, six helicity amplitudes and the differential decay widths are evaluated. Through appropriate angular integrations, we express the helicity flip, helicity nonflip integrated decay rates, and the lepton-side forward-backward asymmetry. We present a numerical analysis of these physical observables. We obtain the mentioned physical quantities by performing fits to the Lattice QCD data using the well-known Boyd-Grinstein-Lebed parametrization. Comparisons with other experimental and theoretical data are also discussed.