Test of lepton flavor universality using B0 ?D*-t+?t decays with hadronic t channels

The branching fraction B(B0?D*-t+?t) is measured relative to that of the normalization mode B0?D*-p+p-p+ using hadronic t+?p+p-p+(p0)?¯t decays in proton-proton collision data at a center-of-mass energy of 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1. The measured ratio is B(B0?D*-t+?t)/B(B0?D*-p+p-p+)=1.70±0.10-0.10+0.11, where the first uncertainty is statistical and the second is related to systematic effects. Using established branching fractions for the B0?D*-p+p-p+ and B0?D*-µ+?µ modes, the lepton universality test R(D*-)B(B0?D*-t+?t)/B(B0?D*-µ+?µ) is calculated, R(D*-)=0.247±0.015±0.015±0.012, where the third uncertainty is due to the uncertainties on the external branching fractions. This result is consistent with the Standard Model prediction and with previous measurements.