Shedding New Light on $\mathcal{R}(D_{(s)}^{(\ast )})$ and $|V_{cb}|$ from Semileptonic ${\bar{B}}_{(s)}\to D_{(s)}^{(\ast )}\ell {\bar{\nu }}_{\ell }$ Decays

Abstract

We compute for the first time the next-to-leading-order QCD corrections to the ${\bar{B}}_{(s)}\to D_{(s)}^{(\ast )}$ form factors at large hadronic recoil. Both the charm-quark-mass and the strange-quark-mass dependent pieces can generate the leading-power contributions to these form factors. Including further various power-suppressed contributions, we perform the combined fits of the considered form factors to both our large-recoil theory predictions and the lattice QCD results, thus improving upon the previous determinations of the lepton-flavour-universality ratios $\mathcal{R}(D^{(\ast )})$ significantly.

Comments: 6 pages plus Supplemental Material, 3 figures, 1 table, 2 ancillary files