SMuK 2023 – scientific programme
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T: Fachverband Teilchenphysik
T 25: Flavor II
T 25.6: Talk
Tuesday, March 21, 2023, 18:15–18:30, HSZ/0304
Analysis of B→ µ ν with inclusive tagging at Belle II — Florian Bernlochner, Jochen Dingfelder, •Daniel Jacobi, Peter Lewis, and Markus Prim for the Belle II collaboration — Physikalisches Institut der Rheinischen Friedrich-Wilhelms-Universität Bonn
BB meson pairs are the dominant decay products of the Υ(4S) resonance, which is produced in large amounts in e+e− collisions at the SuperKEKB collider in Japan, and their decays are measured by the Belle II experiment. Leptonic B meson decays such as B→ µ ν are highly CKM- and helicity-suppressed. In a two-body decay like B→ µ ν, the muon momentum is exactly known in the rest frame of the signal-side B meson. By boosting the signal-side muon into that frame, a better signal resolution and improved sensitivity can thus be achieved compared to the center-of-mass frame. This requires a high-precision for the boost vector, which can be determined from the rest of the event that contains the decay products of the second B meson. At the same time, this information can be used to reconstruct the kinematics of the signal-side B meson. Boosted decision trees are trained to deal with model discrepancies, suppress background and increase signal purity. The hadronic B−→ D0[→ K− π+]π− decay can be used to validate different steps in the analysis of the B→ µ ν decay. This talk will discuss the current status of the analysis for the measurement of the B→ µ ν branching fraction with an integrated luminosity of 364 fb−1 at the Belle II experiment.