SMuK 2023 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 78: Flavor VII
T 78.4: Vortrag
Mittwoch, 22. März 2023, 18:15–18:30, HSZ/0304
Measurement of the ratio of partial branching fractions of hadronicly tagged inclusive B → Xu ℓ ν to B → Xc ℓ ν decays at the Belle experiment. — •Marcel Hohmann1, Phillip Urquijo1, and Kerstin Tackmann2 — 1The University of Melbourne, Melbourne — 2DESY, Hamburg
We present a measurement of the ratio of partial branching fractions of the semi-leptonic inclusive decays, B→ Xuℓν to B→ Xcℓν, where ℓ = e, µ. The measurement is performed on the world leading sample of 772 × 106 B 0.18em −0.18em B pairs collected at the Υ(4S) resonance by the Belle experiment using the state-of-the-art Full Event Interpretation algorithm developed for the Belle II experiment to fully reconstruct the companion B-meson. Identifying inclusive B→ Xuℓν decays is difficult due to the abundance of Cabibbo–Kobayashi–Maskawa (CKM) favored B→ Xcℓν events which share a similar single lepton signature and whose composition are not fully understood. To minimize dependence on modeling of these channels a data-driven B→ Xcℓν description is employed. The ratio is measured via a two-dimensional fit to the lepton momentum, pℓBsig, and four-momentum transfer squared, q2, in the regime pℓBsig > 1.0 Ge −0.1em V, covering approximately 86% and 79% of the B→ Xuℓν and B→ Xcℓν phase-space respectively. The determination of this ratio allows for direct extraction of |Vub| / |Vcb|, corresponding to the length of one of the sides of the Unitarity Triangle. Precise knowledge of this side-length allows for powerful tests of the flavor sector of the standard model and to constrain beyond standard model physics.