Semileptonic b-hadron decays provide various opportunities for the searches of the New Physics~(NP) beyond the Standard Model~(SM). This proceeding covers three recent relevant studies at the LHCb experiment.
There are two new contributions to R(D*), including the simultaneous measurements of R(D) and R(D*) with the muonic tau+ decay using the LHCb Run1 data, and the R(D*) measurement based on the hadronic tau+ decays using the 2015-2016 data.
With these latest results included, the combination of R(D) and R(D*) shows a tension over three standard deviations from the SM predictions.
The first LHCb result of the D* longitudinal polarisation in the B0 -> D*- tau+ nv decay is also presented, where the result is consistent with the SM prediction.