New Physics in inclusive semileptonic $B$ decays

TL;DR

This paper investigates how potential new physics beyond the Standard Model could influence inclusive semileptonic B decays, providing theoretical calculations and experimental fits that yield new constraints on BSM scenarios.

Contribution

It introduces a comprehensive analysis of BSM effects on inclusive B decays using the Weak Effective Theory and performs fits to experimental data to set new bounds.

Findings

New bounds on BSM contributions from inclusive B decay data

Complementary constraints to exclusive decay analyses

Quantitative limits on Wilson coefficients in various BSM scenarios

Abstract

We study inclusive semileptonic $\bar{B}\to X_c \ell \bar{\nu}$ decays ($\ell = e,\mu$) in the presence of generic physics Beyond the Standard Model (BSM) that is heavy compared to the $b$-quark mass. Its effect is encoded in the Wilson coefficients of dimension-six operators of the Weak Effective Theory (WET). We compute the resulting BSM contributions to the experimentally measured kinematic moments and the total decay rate through order $\mathcal{O}(\Lambda_{\rm QCD}^3/m_b^3)$ in the Heavy Quark Expansion, as well as the $\mathcal{O}(\alpha_s)$ corrections for the right-handed vector current. We then perform fits to the full set of available inclusive measurements in several single-mediator scenarios and in the full WET basis. We find qualitatively new bounds in several of these scenarios, complementary to and competitive with constraints from exclusive decays.