Speaker
Description
In the context of lepton flavor universality violation (LFUV) studies, we study different observables related to the $b\to c\tau \bar{\nu}_\tau$ semileptonic decays. These observables are expected to help in distinguishing between different NP scenarios. Since the $\tau$ lepton is very short-lived, we consider three subsequent $\tau$-decay modes, two hadronic $\pi\nu_\tau$ and $\rho\nu_\tau$ and one leptonic $\mu\bar{\nu}_\mu\nu_\tau$, which have been previously studied for $\bar{B} \to D^{(*)}$ decays. This way the differential decay width can be written in terms of visible (experimentally accessible) variables of the massive particle created in the $\tau$ decay. There are seven different $\tau$ angular and spin asymmetries that are defined in this way and that can be extracted from experiment. In addition to these asymmetries, we study the $d^2\Gamma_d/(d\omega d\cos\theta_d)$, $d\Gamma_d/d\cos\theta_d$ and $d\Gamma_d/dE_d$ distributions. We present numerical results for the $\Lambda_b\to\Lambda_c\tau\bar{\nu}_\tau$ semileptonic decay, which is expected to be measured with precision at the LHCb.
