5. Theoretical Physics (CSN4)

# Global fits to b → cτν transitions

## by Ana Penuelas Martinez (Valencia Univ.)

Europe/Rome
Aula Salvini (LNF)

### Aula Salvini

#### LNF

Via Enrico Fermi, 40 00044 Frascati (Roma)
Description

We perform a general model-independent analysis of b cτντ transitions, including measurements of RD , RD, their q2 differential distributions, the recently measured longitudinal Dpolarization FD, and constraints from the Bc τντ lifetime, each L of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected b cτντ observables, such as the baryonic transition Λb Λcτντ, the ratio RJ/ψ, the forward-backward asymmetries AD(), FB the τ polarization asymmetries PD() , and the longitudinal Dpolarization fraction τ F D. The latter shows presently a slight tension with any new-physics model, such L that an improved measurement could have an important impact.