Search for the Rare Decays B --> Kl^+l^- and B --> K^*(892)l^+ l^-

TL;DR

This paper reports a search for rare B meson decays into K or K* mesons with lepton pairs, setting upper limits close to Standard Model predictions using data from the BABAR detector.

Contribution

First search for these specific rare decays with the BABAR detector, providing upper limits near Standard Model expectations.

Findings

Upper limit BF(B --> Kl^+l^-) < 0.6 x 10^{-6}

Upper limit BF(B --> K^*l^+l^-) < 2.5 x 10^{-6}

Results are close to Standard Model predictions.

Abstract

We present preliminary results from a search for the flavor-changing neutral current decays B-->Kl^+l^- and B-->K^*(892)l^+l^- using a sample of 22.7 x 10^6 Upsilon(4S)-->B anti-B decays collected with the BABAR detector at the PEP-II B Factory. We have reconstructed the following final states: B^+ --> K^+l^+l^-, B^0 --> K^0l^+l^- (K_s^0 --> pi^+pi^-), B^+ --> K^{*+}l^+l^- (K^{*+} --> K_s^0 pi^+), and B^0 --> K^{*0}l^+l^- (K^{*0} --> K^+pi^-), where l^+l^- is either an e^+e^- or mu^+mu^- pair. We obtain the 90% C.L. upper limits BF(B --> Kl^+l^-)< 0.6 x 10^{-6} and BF(B --> K^*l^+l^-)<2.5 x 10^{-6}, close to the Standard Model predictions for these branching fractions.