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T: Fachverband Teilchenphysik
T 73: Flavour Physics IV
T 73.7: Vortrag
Donnerstag, 3. April 2025, 17:45–18:00, VG 1.103
Measurement of angular coefficients of B → D* ℓ νℓ using Belle II data — Florian Bernlochner1, Markus Prim1, Michael Hedges2, and •Maximilian Hoverath1 — 1Physikalisches Institut der Rheinischen Friedrich-Wilhelms-Universiät Bonn — 2Fermi National Accelerator Laboratory
A precise determination of the CKM matrix element Vcb is essential for understanding quark-flavor transitions within the Standard Model (SM). In addition to measuring Vcb, semileptonic decays provide a valuable opportunity to probe lepton-flavor universality (LFU), a fundamental feature of the SM that predicts universal gauge couplings for leptons. Any observed deviation from LFU would indicate the presence of physics beyond the SM. In this work, we analyze the exclusive semileptonic decay B → D* ℓ νℓ using hadronic tagging and Belle II data to determine the angular coefficients. These coefficients allow for the determination of Vcb and the associated form factors, which parameterize the hadronic interaction in the decay. Additionally, we test LFU by measuring asymmetries between the electron and muon channels. Using helicity angles cosθℓ, cosθV, χ, and the hadronic recoil parameter w, we fully describe the kinematics of the decay product by reconstructing the angular coefficients in bins of w. We subtract the background in a model-independent way by fitting the missing mass squared and correct the measured distributions for migration and selection effects.