A test of lepton flavour universality with a measurement of $R(D^{(*)})$ using semileptonic B tagging and leptonic $\tau$ decays

Sumitted to PubDB: 2024-07-02

Category: Physics / performance paper, Visibility: Latest Version Public

Authors	Florian Bernlochner, Jochen Dingfelder, Peter Lewis, Alina Manthei, Markus Prim
Date	2025-09-05
Working group	Semileptonic and Missing Energy Decay
Belle II Number	BELLE2-PUB-DRAFT-2024-014
Abstract	We report the measurement of the branching fractions $\mathcal{R}(D^{()}) = \frac{\mathcal{B}(\overline{B} \to D^{()} \tau \bar{\nu}_\tau)}{\mathcal{B}(\overline{B} \to D^{(*)} \ell \bar{\nu}_\ell)}$ with $\ell$ denoting either an electron or a muon. This measurement tests the universality of the charged-current weak interaction and utilises 364fb$^{-1}$ of integrated luminosity of electron-positron collision data collected with the Belle~II detector. Signal candidates are reconstructed in collision events in which one of the $B$ mesons in the $\Upsilon(4S) \to B\overline B$ decay is fully reconstructed in semileptonic modes, and the $\tau$ is reconstructed using leptonic decays.
ArXiv	https://arxiv.org/abs/2504.11220
Inspire	https://inspirehep.net/literature/2912132
Journal	Phys.Rev.D
Authorship confirmation page	https://authors.belle2.org/#61
Analysis	Measurement of $R(D^{(*)})$ using semileptonic tagging and leptonic $\tau$ decays