In the context of lepton flavor universality violation (LFUV) studies, we study different observables related to the b→cτν¯τ semileptonic decays. These observables are expected to help in distinguishing between different NP scenarios. Since the τ lepton is very short-lived, we consider three subsequent τ-decay modes, two hadronic πντ and ρντ and one leptonic μν¯μντ, which have been previously studied for B¯→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 τ decay.
There are seven different τ 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 d2Γd/(dωdcosθd), dΓd/dcosθd and dΓd/dEd distributions.
We present numerical results for the Λb→Λcτν¯τ semileptonic decay, which is being measured with precision at the LHCb.