We report a measurement of the branching fraction ratios R(D(∗)) of B¯→D(∗)τ-ν¯τ relative to B¯→D(∗) -ν¯ (where =e or μ) using the full Belle data sample of 772×106BB¯ pairs collected at the (4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured values are R(D)=0.375±0.064(stat)±0.026(syst) and R(D∗)=0.293±0.038(stat)±0.015(syst). The analysis uses hadronic reconstruction of the tag-side B meson and purely leptonic τ decays. The results are consistent with earlier measurements and do not show a significant deviation from the standard model prediction.
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - 26 Oct 2015|