Erlangen 2026 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 94: Flavour Physics VI
T 94.5: Vortrag
Freitag, 20. März 2026, 10:00–10:15, KH 01.011
R(D*) measurements with ATLAS Run 2 data — •Laily Sultanaliyeva1, Leonid Gladilin2, and Vladimir Tikhomirov2 — 1University of Bonn, Bonn, Germany — 2Moscow, Russia
Semileptonic decays of hadrons can be used for testing the equality of the couplings of the three charged leptons to the gauge bosons, i.e. Lepton Flavour Universality (LFU). Sensitive to LFU violation ratios of branching fractions for various hadrons decays have been previously studied by BaBar, Belle and LHCb experiments. The aim of this analysis is to measure R(D*) ≡ B (B0→ D*−τ+ντ)/B(B0→ D*−µ+νµ) with proton-proton (pp) collisions data collected by the ATLAS experiment during LHC Run 2 and compare with the current world-average result, which now exceeds the Standard Model predictions by ∼ 2.7σ.
The ratio of branching fractions R(D*) is measured with data recorded during pp collisions with √s = 13 TeV corresponding to the integrated luminosity of 140 fb−1. The τ± leptons are reconstructed through the semileptonic decay τ±→ µ±ν_µντ, while for D* mesons the following decay chain is used: D*±→ D0 π± → (K∓π±)π±. Both τ− and µ− decay modes of B0 mesons have the same number of detectable particles in the final state, and thus can be selected and analysed together. A multi-dimesional fit then can be used to separate two signal processes from each other as well as from background processes. In this talk the current state of the analysis will be presented.
Keywords: ATLAS; Semileptonic decays; B-hadrons; B-physics