Measurement of the τ Lepton Polarization and R(D^{*}) in the Decay B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ}
Department
Physics
Document Type
Article
Publication Date
5-2017
Embargo Period
7-3-2018
Abstract
We report the first measurement of the τ lepton polarization Pτ (D ∗ ) in the decay B¯ → D ∗ τ −ν¯τ as well as a new measurement of the ratio of the branching fractions R(D ∗ ) = B(B¯ → D ∗ τ −ν¯τ )/B(B¯ → D ∗ ` −ν¯`), where ` − denotes an electron or a muon, and the τ is reconstructed in the modes τ − → π −ντ and τ − → ρ −ντ . We use the full data sample of 772×106 BB¯ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our results, Pτ (D ∗ ) = −0.38±0.51(stat.) +0.21 −0.16(syst.) and R(D ∗ ) = 0.270 ± 0.035(stat.) +0.028 −0.025(syst.), are consistent with the theoretical predictions of the Standard Model.
Journal Title
Physical Review Letters
Journal ISSN
0031-9007
Volume
118
Issue
21
Digital Object Identifier (DOI)
10.1103/PhysRevLett.118.211801
Comments
Preprint.