2017/09/11 by S. Hirose, Hirose, S.
Earth and Planetary Sciences · Physics and Astronomy · #FOS: Physical sciences #Geological and Geophysical Studies #High Energy Physics - Experiment (hep-ex) #Quantum Chromodynamics and Particle Interactions #Seismic Imaging and Inversion Techniques
paper · pdf · doi:10.48550/arxiv.1709.03235
openalex publication_date 2017/09/11 · openalex created_date 2024/04/10 · openalex updated_date 2026/07/28
The semitauonic decay B → D^* τ- ντ is sensitive to new physics beyond the Standard Model (SM) that has an enhanced coupling to the τ lepton. In the ratio of branching fractions R(D^*) = B(B → D^* τ- ντ) / B(B → D^* ℓ- ν_ℓ), where ℓ- = e- or μ-, a 3.3σ anomaly was observed. In order to investigate the anomaly further, Belle performed a new R(D^*) measurement using one-prong hadronic τ decays, which was statistically independent of the previous two measurements. This measurement included the first measurement of the τ polarization Pτ(D^*) using the kinematics of the two-body decays. The obtained results, R(D^*) = 0.270 ± 0.035 (\rm stat) +0.028-0.025 (\rm syst) and Pτ(D^*) = -0.38 ± 0.51 (stat) +0.21-0.16 (syst), were consistent both with the SM and the world-average R(D^*). Including this result, the R(D^*) anomaly became 3.4σ away from the SM prediction.