Filippo Dattola

12 May 2021

Abstract: This contribution illustrates a new search for the flavor-changing neutral-current decay B+ → K+νν performed by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. In this study, a sample corresponding to an integrated luminosity of 63 fb−1 collected at the Υ(4S) resonance and an additional sample of 9 fb−1 collected at an energy 60 MeV below the resonance are used. A novel technique, based on an inclusive tagging method and exploiting the topological features of the B+ → K+νν decay, is employed and it provides a higher signal efficiency with respect to the methods used in the previous searches. No significant signal is observed. An upper limit of 4.1 × 10−5 is set on the B+ → K+νν branching fraction at the 90 % confidence level.

Keyword(s): Moriond EW ; Inclusive Tagging ; B+ → K+νν