Search for the B+ -> K+vv Decay Using Semi-Leptonic Tags

TL;DR

This paper reports an updated search for the rare B+ -> K+vv decay using semi-leptonic tagging, setting an upper limit on its branching fraction based on data from the BABAR experiment.

Contribution

The study introduces an improved method for searching for B+ -> K+vv decays using semi-leptonic tags and provides the most recent upper limit on its branching fraction.

Findings

38 candidate events observed with expected background of 31 +/- 12

Upper limit on branching fraction set at 4.5 x 10^-5 (90% CL)

Enhanced sensitivity in rare decay search using semi-leptonic tagging

Abstract

We present an update of the search for the flavor-changing neutral current B+ -> K+vv decay using 351 x 10^6 BB pairs collected at the Y(4S) resonance with the BABAR detector at the SLAC PEP-II B factory. Due to the presence of two neutrinos in the final state, we require the reconstruction of the companion B in the event through the decay channel B- -> D0l-v. We find 38 candidates in the data with an expected background of 31 +/- 12. This allows us to set an upper limit on the branching fraction for B+ -> K+vv of 4.5 x 10^-5 at 90% confidence level.