Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 7: Flavour physics V

T 7.3: Talk

Monday, March 15, 2021, 16:30–16:45, Tg

R(D^**) at Belle II with leptonic τ decays — Ariane Frey, •Noreen Rauls, and Benjamin Schwenker — II. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Deutschland

Semileptonic B meson decays to τ leptons are used to probe the standard model. This can be investigated in the rate of the semitauonic decay B → D^** τ ν, which can be enhanced, for instance, by the presence of an additional charged Higgs boson.
R(D^**) is defined as the ratio of the branching ratio B → D^** τ ν by the averaged branching ratio of both light leptons B → D^** ℓ ν and is hence sensitive to new physics that couples differently to light and heavy leptons.
At the Belle II experiment, B mesons are always produced in pairs at the Υ(4S) resonance. One B meson is reconstructed using the B decay modes stated above. Here, the τ lepton is reconstructed in the leptonic mode. For the reconstruction of the other B meson the Full Event Interpretation (FEI) is chosen. The FEI algorithm reconstructs the other B meson using multivariate classifiers in various different hadronic decay modes.
This talk will present first studies on the reconstruction of the B meson decays used to extract R(D^**) conducted on Belle II Monte Carlo samples as well as an outlook on future plans.