1. David Doll, Ilya Narsky, David Hitlin B + K + νν

2. Theory These FCNC (Flavor Changing Neutral Current) decays proceed via Z- penguin or W-box diagrams within the Standard Model, and are consequently quite suppressed. SM predicts a Branching Fraction of 3.8 x 10 -6. Several other theories (multi-Higgs doublet model, minimal super- symmetry (SUSY), etc.) imply an increase in b svv, which invites an investigation of this channel.

3. Previous Analyses For This Mode Semileptonic tag: B (K + νν)<7.0*10 -5 Hadronic tag : B (K + νν)<6.7*10 -5 Combined: B (K + νν)<5.2*10 -5 Previous BaBar results Most Recent Belle results, presented at FPCP 2007:

4. Tag Selection We are using Runs 1 through 5 data (319 fb -1 ) We are using the semileptonic tagged events, with the D 0 decaying via K - π +, K - π + π - π +, K - π + π 0 B+B+ ν ν K+K+ B+B+ D0D0 l+l+ ν

5. Signal Selection We use a Random Forest (Bagged Decision tree) multivariate classifier to separate signal from background. We use a ‘double tag’ sample (both B mesons decay semileptonically) to evaluate the systematic uncertainty on the signal region. signal Different background processes

6. Results (Journal Draft under review) We predict 30.7 ± 10.7 events in the signal box with a signal efficiency of. Within the signal box we see 38 events, allowing us to set an upper limit of at 90% confidence level. Signal Region