Charged Current Anomalies with Baryons

TL;DR

This paper explores angular observables in Lambda_b decays to understand and distinguish potential new physics explanations for the observed anomalies in b to c tau neutrino transitions, emphasizing measurements that could clarify these anomalies.

Contribution

It identifies specific angular observables in Lambda_b decays that can help discriminate between Standard Model and new physics explanations for B decay anomalies.

Findings

Angular observables can discriminate new physics models.

Measurement of R_{Lambda_c} does not alter the current anomaly picture.

Certain angular observables have strong potential to distinguish new physics.

Abstract

Motivated by the first observation of $\Lambda_b\to\Lambda_c~\tau\bar{\nu}$ by LHCb, we discuss various observables that can be derived from angular distribution of this decay which, if measured, could be essential for explanation of the $b\to c\tau\bar{\nu}$ anomalies. Furthermore, we show that the measurement of $R_{\Lambda_c}=\mathcal{B}(\Lambda_b\to\Lambda_c\tau\bar{\nu})/\mathcal{B}(\Lambda_b\to\Lambda_c\mu\bar{\nu})$ does not change the current global picture arising from $R_D^{\rm}$ and $R_{D^*}^{\rm}$ being larger than predicted in the Standard Model. Finally, we show the example of a few angular observables, with and without a secondary decay, that could have a strong discriminating power on New Physics.