$b \to c$ semileptonic sum rule: Extension to angular observables

TL;DR

This paper extends $b o c$ semileptonic sum rules to include angular observables, providing a new consistency check for experimental results and exploring corrections relevant for phenomenology.

Contribution

It introduces new sum rules involving angular observables in $b o c l u$ decays, valid in the heavy quark limit, and analyzes their corrections and phenomenological implications.

Findings

Sum rules hold exactly in the heavy quark limit.

Corrections to the sum rules are analyzed for realistic scenarios.

Implications for testing lepton flavor universality are discussed.

Abstract

Lepton flavor universality is a key prediction of the Standard Model of particle physics and any violation of it immediately indicates the existence of new physics. Given the recent more than $4\sigma$ discrepancy in charged current semileptonic B meson decays and the absence of evident signals at the large hadron collider, independent cross-checks become invaluable. In this context, $b \to c$ semileptonic sum rules based on heavy quark symmetry are interesting since they allow us to check the consistency of experimental results. In this paper, we report newly found sum rules among angular observables of mesonic and baryonic $b\to c l \overline{\nu}$ decays holding exactly in the large mass limit of heavy quarks. Moreover, we investigate corrections to the sum rule in realistic situations and discuss phenomenological implications.