Next-to-leading order QCD corrections to the form factors of $B$ to scalar meson decays

TL;DR

This paper calculates next-to-leading order QCD corrections to $B$ to scalar meson form factors using light-cone sum rules, providing refined predictions for decay processes and angular observables, with results showing modest NLO effects.

Contribution

It introduces a detailed NLO calculation of $B$ to scalar meson form factors via light-cone sum rules, including $q^2$ dependence and phenomenological predictions.

Findings

NLO corrections increase form factors by about 5%.

Predicted branching ratios and angular observables for semi-leptonic $B$ decays.

Form factors are reconstructed across the entire kinematic range.

Abstract

We calculate the next-to-leading order QCD corrections to $B$ to scalar meson form factors from QCD light-cone sum rules with $B$ meson light-cone distribution amplitudes. We demonstrate that the $B$ meson-to-vacuum correlation functions can be factorized into the convolution of short-distance coefficients and light-cone distribution amplitudes at the one-loop level and find that only $\phi_B^+(\omega,\mu)$ contributes to the form factors. We then employ the $z$-parameterization combined with constraints from strong coupling constants to reconstruct the $q^2$ dependence of the form factors in the whole kinematic allowed regions. Due to the large cancellations between the hard functions and the jet functions, the next-to-leading order results show a modest increase of approximately 5\% compared to the leading order results. Based on the results of form factors, we predict the branching ratios of semi-leptonic $B\to S\ell\bar{\nu}_\ell$ and $B\to S\nu_\ell\bar{\nu}_\ell$ processes, as well as several angular observables, such as forward-backward asymmetries, "flat terms" and lepton polarization asymmetries. We compare these results with calculations from other methods. Experimental verification of these results is required in future experiments.