Greg Ciezarek (CERN)
First joint measurement of R(D) and R(D*) at LHCb
Abstract: Previous measurements of the ratio of semileptonic decays R(D*) = B(B->D*taunu)/B(B->D*munu) and R(D0) = B(B->Dtaunu)/B(B->Dmunu) from Babar, Belle, and LHCb hint at a deviation from lepton universality. This seminar presents the first joint measurement of both R(D*) and R(D) at LHCb, reconstructed with the tau->mununu decay mode in the D*+mu and D0mu final states and assuming isospin symmetry. This pathfinder analysis is based on Run 1 data. This result supersedes the previous LHCb measurement of R(D*+)) alone with the muonic decay of the tau.