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T: Fachverband Teilchenphysik

T 30: Flavour Physics 3

T 30.6: Talk

Tuesday, March 22, 2022, 17:30–17:45, T-H15

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 suppress background and increase signal purity. This talk will discuss the current status of the analysis and present approaches to maximize the sensitivity of the measurement of B→ µ ν at Belle II, and will additionally provide an outlook on the search for sterile neutrinos.