Speaker
Description
In recent years, evidence of Lepton Flavour Universality Violation has been observed in semi-leptonic decays associated with the charged-current transition 𝑏→𝑐𝑙𝜈 ̅ by BABAR, Belle and LHCb experiments, up to 3 standard deviations (3σ). While for the neutral-current transition 𝑏𝑏 ̅→𝑙^+ 𝑙^−, the BABAR collaboration in 2020 reported a discrepancy of 1.8σ in the leptonic decay of the ϒ(3s) meson. Since the new physics operator that modifies the charged transition also contributes to the neutral process, in this work we study the impact of these measurements on a new physics model consisting of an extra triplet of left-handed vector-bosons (W', Z') that coupled preferably to fermions of the third family. We observe that this model cannot simultaneously explain the recent measurement obtained by BABAR for ϒ(3s) and the observables given by the transition 𝑏→𝑐𝑙𝜈 ̅.
