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This contribution illustrates a new search for the flavor-changingneutral-current decay ${B^+ \to K^+ \nu \bar \nu}$ performed by the Belle IIexperiment at the SuperKEKB asymmetric-energy electron-positron collider. Inthis study, a sample corresponding to an integrated luminosity of $63\,\rm{fb}^{-1}$ collected at the $\rm \Upsilon(4S)$ resonance and an additionalsample of $9\, \rm{fb}^{-1}$ collected at an energy $60\, \rm MeV$ below theresonance are used. A novel technique, based on an inclusive tagging method andexploiting the topological features of the ${B^+ \to K^+ \nu \bar \nu}$ decay,is employed and it provides a higher signal efficiency with respect to themethods used in the previous searches. No significant signal is observed. Anupper limit of $4.1 \times 10^{-5}$ is set on the ${B^+ \to K^+ \nu \bar \nu}$branching fraction at the $90\, \%$ confidence level.

Search for $B^{+} \to K^{+} \nu \bar \nu$ decays with an inclusive tagging method at the Belle II experiment