Lepton universality tests and searches for new physics in charged current decays at Belle II

Sumitted to PubDB: 2024-01-10

Category: Proceeding, Visibility: Public

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Authors Henrik Junkerkalefeld
Date 2023-12-29
Belle II Number BELLE2-CONF-PROC-2023-049
Abstract We present recent tests of lepton universality as crucial probes of the Standard Model in semileptonic B-meson decays at Belle II. All presented analyses use a data sample collected at the Υ(4S) resonance by the Belle II experiment corresponding to an integrated luminosity of 189fb1. We report three analyses that probe light-lepton universality: The first measurement of a complete set of five angular asymmetries using B¯0D+ν¯ decays, followed by a measurement of the forward-backward asymmetry in untagged B¯0D+ν¯ decays, and finally, measurements of the branching-fraction ratios R(De/μ+)=B(B¯0D+eν¯e)/B(B¯0D+μν¯μ), using the same untagged data set, along with the first measurement of the inclusive light-lepton ratio R(Xe/μ)=B(B¯Xeν¯e)/B(B¯Xμν¯μ). Furthermore, we present two tests of heavy-to-light lepton universality. In the first test, we report the measurement of the branching-fraction ratio R(Dτ/) using hadronic tagging. In the second test, we present the first measurement of the inclusive ratio R(Xτ/). All presented results are consistent with their corresponding Standard Model predictions and, where applicable, with the experimental world averages.

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