Year: 2021
Type: article
Abstract: We present the first lattice-QCD determination of the form factors describing the semileptonic decays ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{c}^{*}(2595){\ensuremath{\ell}}^{\ensuremath{-}}\overline{\ensuremath{\nu}}$ and ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{c}^{*}(2625){\ensuremath{\ell}}^{\ensuremath{-}}\overline{\ensuremath{\nu}}$, where the ${\mathrm{\ensuremath{\Lambda}}}_{c}^{*}(2595)$ and ${\mathrm{\ensuremath{\Lambda}}}_{c}^{*}(2625)$ are the lightest charm baryons with ${J}^{P}={\frac{1}{2}}^{\ensuremath{-}}$ and ${J}^{P}={\frac{3}{2}}^{\ensuremath{-}}$, respectively. These decay modes provide new opportunities to test lepton flavor universality and also play an important role in global analyses of the strong interactions in $b\ensuremath{\rightarrow}c$ semileptonic decays. We determine the full set of vector, axial vector, and tensor form factors for both decays but only in a small kinematic region near the zero-recoil point. The lattice calculation uses three different ensembles of gauge-field configurations with $2+1$ flavors of domain-wall fermions, and we perform extrapolations of the form factors to the continuum limit and physical pion mass. We present Standard Model predictions for the differential decay rates and angular observables. In the kinematic region considered, the differential decay rate for the ${\frac{1}{2}}^{\ensuremath{-}}$ final state is found to be approximately 2.5 times larger than the rate for the ${\frac{3}{2}}^{\ensuremath{-}}$ final state. We also test the compatibility of our form-factor results with zero-recoil sum rules.
Authors: Stefan Meinel, Gumaro Rendon
Institutions: University of Arizona, Brookhaven National Laboratory
Language: Latvian
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Awards: G1039895795, G111697547, G241279073, G272672434, G3204085874, G3226045097, G357145406, XSEDE 2.0: Integrating, Enabling and Enhancing National Cyberinfrastructure with Expanding Community Involvement, G3850097093, G4354484304, G4382344593, G4392917094, G4972998915, G498139845, G5590740066, G5633341255, G5765906131, G6733788163, G6806689448, G7406122311, G7463374569, G7861570460, G872144517, G8866302460, UNIVERSITY OF ARIZONA HIGH ENERGY PHYSICS PROGRAM, G969889393
OpenAlex ID: W3136385113