New physics in the kinematic distributions of $\bar B\to D^{(*)}\tau^-(\to\ell^-\bar\nu_\ell\nu_\tau)\bar\nu_\tau$

TL;DR

This paper analyzes the kinematic distributions of  decays, introducing new observables and exploring potential new physics effects through detailed theoretical formulas and comparisons.

Contribution

It provides analytic formulas for 3-fold differential decay rates and explores new physics effects in  decays using an effective field theory approach.

Findings

Derived explicit formulas for decay distributions.

Identified observables sensitive to new physics.

Compared Standard Model predictions with new physics scenarios.

Abstract

We investigate the experimentally-accessible kinematic distributions of the $\bar B\to D^{(*)}\tau^-(\to\ell^-\bar\nu_\ell\nu_\tau)\bar\nu_\tau$ decays. Specifically, we study the decay rates as functions of the $B\to D^{(*)}$ transferred squared momentum, the energy of the final charged lepton and the angle of its 3-momentum relative to the 3-momentum of the recoiling $D^{(*)}$. The angular distribution allows to introduce new observables, like a forward-backward asymmetry, which are complementary to the total rates. We present analytic formulas for the observable 3-fold 5-body differential decay rates, study the predictions in the Standard Model and investigate the effects in different new-physics scenarios that we characterize using an effective field theory framework.