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T: Fachverband Teilchenphysik

T 29: Flavour Physics II

T 29.6: Talk

Tuesday, March 17, 2026, 17:30–17:45, KH 01.011

Search for B_c⁺ → B_s⁰ µ⁺ ν_µ decays at LHCb — •Mikhail Chekal and Marco Gersabeck — Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany

Semileptonic decays are useful for probing new physics as they can be used to test lepton flavour universality. To date, B_c⁺ → J/ψ ℓ⁺ ν_ℓ remains the only semileptonic B_c⁺ decay channel to be observed. A search for the semileptonic decay B_c⁺ → B_s⁰ µ⁺ ν using the LHCb Run 3 data collected in 2024–2025 is presented. The strategy is to extract the B_c⁺ → B_s⁰ π⁺ yield, which serves as the normalization channel, as well as the combined B_c⁺ → B_s⁰ µ⁺ ν and B_c⁺ → B_s^*0 µ⁺ ν, and compute their ratio of branching fractions. The B_s⁰ candidates are reconstructed as B_s⁰ → D_s⁻ (K⁺ K⁻ π⁻) π⁺ and the results will later be combined with those of the second group working on the B_s⁰ → J/ ψ φ channel. Methods, used for B_s⁰ and B_c⁺ candidates selection for the normalization and signal channels are presented.

Keywords: semileptonic; LHCb