Lepton-flavour universality tests with semi-leptonic B decays at LHCb

TL;DR

This paper reports a measurement of the ratio R(D*) in semileptonic B decays involving tau leptons at LHCb, testing lepton-flavour universality and probing for potential new physics effects.

Contribution

It presents the first measurement of R(D*) using 3-prong tau decays at LHCb, providing new data for lepton-flavour universality tests.

Findings

Measurement of R(D*) with 3-prong tau decays

Results consistent with Standard Model predictions

Enhanced sensitivity to new physics in B decays

Abstract

In the Standard Model, the three charged lepton are identical copies of each other, apart from mass differences. Experimental tests of this feature in decays of semileptonic b hadrons, such as $B\rightarrow D^* \tau\ nu$, are highly sensitive to New Physics particles which preferentially couple to the 3rd generation.A measurement of $R(D^{*-})$ using 3-prong $\tau$ decays performed by LHCb is reported.