${\bar B} \to D^* \ell^- {\bar\nu}_\ell$ Decays: Angular Distributions and New Physics

TL;DR

This paper discusses angular distributions in B meson decays to D* and leptons, aiming to identify potential new physics contributions and their Lorentz structures through detailed angular analysis.

Contribution

It introduces comprehensive angular distributions for B to D* decays with general new physics contributions, enabling detailed identification of NP Lorentz structures.

Findings

Angular distributions can distinguish different NP Lorentz structures.

Distributions can reveal non-SMEFT (non-decoupling) NP effects.

Method provides a way to identify and characterize new physics in B decays.

Abstract

At the present time, there are hints of new physics (NP) in several observables involving $b \to c \ell^- {\bar\nu}_\ell$ decays. In this talk, I describe measurable angular distributions for ${\bar B} \to D^* \mu^- {\bar\nu}_\mu$ and ${\bar B} \to D^* \tau^- (\to \pi^- \nu_\tau) {\bar\nu}_\tau$ decays, including the most general NP contributions. These angular distributions contain enough information to pin down the Lorentz structure of the NP, which will help to identify it. They also have the ability to reveal the presence of non-SMEFT (non-decoupling) NP.