SMuK 2023 – scientific programme

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T: Fachverband Teilchenphysik

T 129: Flavor X

T 129.1: Talk

Thursday, March 23, 2023, 17:30–17:45, HSZ/0304

New physics in b→ cτν — Marco Fedele¹, Monika Blanke^1,2, Andreas Crivellin^3,4, Syuhei Iguro^1,2, Teppei Kitahara^5,6,7, •Ulrich Nierste¹, and Ryoutaro Watanabe⁸ — ¹Institut für Theoretische Teilchenphysik (TTP), Karlsruhe Institute of Technology (KIT) — ²Institut für Astroteilchenphysik (IAP), Karlsruhe Institute of Technology (KIT) — ³Paul Scherrer Institut — ⁴Physik-Institut, Universität Zürich — ⁵Institute for Advanced Research & Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University — ⁶KEK Theory Center, IPNS, Tsukuba — ⁷CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing — ⁸INFN, Sezione di Pisa

The branching fractions of the decays B→ Dτν and B→ D^*τν have been measured by BaBar, Belle, and LHCb. The combination of these measurements indicates an enhancement of the b→ cτν amplitude w.r.t. the Standard-Model prediction by 3.2σ. This finding is in in tension with the measurement of B(Λ_b→Λ_cτν), which is related to the former two branching ratios by a sum rule. I discuss the implications of this sum rule for future measurements and assess popular scenarios of new physics postulating either a charged Higgs boson or leptoquarks.