$B_{(s)} \rightarrow D^{**}_{(s)}$ form factors in HQEFT and model independent analysis of relevant semileptonic decays with NP effects

TL;DR

This paper systematically calculates $B_{(s)}$ to $D^{**}_{(s)}$) form factors using HQEFT and QCD sum rules, enabling a model-independent analysis of semileptonic decays with potential new physics effects.

Contribution

It provides the first comprehensive calculation of form factors for $B_{(s)}$ to $D^{**}_{(s)}$ decays including scalar and tensor form factors, incorporating next-to-leading order heavy quark expansion.

Findings

Predicted differential decay widths and branching fractions.

Derived universal wave functions for form factors.

Analyzed potential new physics contributions in semileptonic decays.

Abstract

The form factors of $B_{(s)}$ decays into P-wave excited charmed mesons (including $D^*_0(2300)$, $D_1(2430)$, $D_1(2420)$, $D^*_2(2460)$ and their strange counterparts, denoted generically as $D^{**}_{(s)}$) are systematically calculated via the QCD sum rules in the framework of heavy quark effective field theory (HQEFT). We consider contributions up to the next leading order of heavy quark expansion and give all the relevant form factors, including the scalar and tensor ones only relevant for possible new physics effects. The expressions for the form factors in terms of several universal wave functions are derived via heavy quark expansion. These universal functions can be evaluated through QCD sum rules. Then, the numerical results of the form factors are presented. With the form factors given here, a model independent analysis of relevant semileptonic decays $B_{(s)} \rightarrow D^{**}_{(s)} l \bar{\nu}_l$ is performed, including the contributions from possible new physics effects. Our predictions for the differential decay widths, branching fractions and ratios of branching fractions $R(D^{**}_{(s)})$ may be tested in more precise experiments in the future.