$B_c \to D^{(*)}\tau \bar \nu_\tau$ processes in an effective field theory approach

TL;DR

This paper investigates rare semileptonic $B_c$ decays involving $b o u au ar u_ au$ transitions using an effective field theory framework, constraining new physics couplings with existing data and analyzing their effects on observables.

Contribution

It introduces a comprehensive EFT analysis of $B_c o D^{(*)} au ar u_ au$ decays, considering complex and real new couplings and their impact on various observables.

Findings

Constraints on new couplings from current data.

Sensitivity of branching ratios and angular observables to new physics.

Potential deviations from Standard Model predictions.

Abstract

We present a compressive study on rare semileptonic $B_c \to D^{(*)}\tau \bar \nu_\tau$ decays involving $b \to u \tau \bar \nu_\tau$ quark level transitions in an effective field theory approach. We consider the presence of an additional (pseudo)vector and (pseudo)scalar type interactions which can be either complex or real and constrain the new couplings using the existing data on $R_{D^{(*)}}$, $R_{J/\psi}$, $R_\pi^l$, Br($B_{u,c} \to \tau \bar \nu_\tau$) and Br($B \to\pi \tau \bar \nu_\tau$) parameters. In order to segregate the sensitivity of new coefficients, we check the effects of these couplings on the branching ratios, lepton non-universality and various angular observables of $B_c \to D^{(*)}\tau \bar \nu_\tau$ processes.