Erlangen 2026 – scientific programme

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T: Fachverband Teilchenphysik

T 94: Flavour Physics VI

T 94.4: Talk

Friday, March 20, 2026, 09:45–10:00, KH 01.011

Angular analysis of B⁰ → D^*τν in Run 2 at the LHCb experiment — Tobias Knospe¹, Johannes Albrecht¹, Greg Ciezarek², Marco Gersabeck³, Lucia Grillo⁴, •Biljana Mitreska⁵, Chris Parkes⁵, Manuel Schiller⁴, Derek Yeung⁵, and Havva Hasret Nur⁴ — ¹TU Dortmund University, Dortmund, Germany — ²CERN, Geneva, Switzerland — ³Albert-Ludwigs-Universität Freiburg, Freiburg, Germany — ⁴University of Glasgow, Glasgow, UK — ⁵The University of Manchester, Manchester, UK

The global average of the ratio R(D^*) between the B⁰ → D^*τν and B⁰ → D^*µν branching fractions is at tension with the SM prediction. The angular structure of the b → c ℓ ν transition using effective field theory allows to probe potential New Physics (NP) effects with greater sensitivity than a measurement of the branching fraction. An angular analysis of the B⁰ → D^*τν decay is presented, based on proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 1.6 fb⁻¹. The signal distribution is extracted through a multidimensional fit to the data, using templated distributions derived from both simulation and data control samples. The R(D^*) ratio and several NP Wilson coefficients are measured in different combinations. Additionally, the R(D^*) ratio as well as the hadronic form factors are measured in a Standard Model scenario using BGL and BLPR parameterizations.

Keywords: RD*; LFU; Lepton Flavour Universality; Angular analysis; New Physics