Soft photon corrections to semileptonic B meson decays

The combined analysis of data from the BaBar Belle and LHCb experiments shows the 3 8 sigma anomaly in the B meson semileptonic decays so called R D anomaly In this talk long distance QED corrections to B gt D tau nu relative to B gt D mu nu in the standard model is discussed We point out that the QED corrections to the ratio R D are not negligible The reason is that long distance QED corrections depend on the masses and relative velocities of the daughter particles muon mode is a relativistic decay but tau mode is not This talk is based on PhysRevLett 120 261804