Penguin Mediated B Decays at BABAR

TL;DR

This paper presents preliminary measurements of branching fractions for penguin-mediated B decays at BABAR, providing new experimental data on rare decay modes and setting upper limits for others, advancing understanding of flavor-changing neutral currents.

Contribution

It reports the first measurements of several penguin-mediated B decay branching fractions and establishes upper limits for rare decay modes using BABAR data.

Findings

Measured branching fractions for multiple B decay modes.

Set upper limits on flavor-changing neutral current decays.

Provided experimental data to test Standard Model predictions.

Abstract

We report on preliminary results of searches for penguin mediated B decays based on 20.7 fb^{-1} of data collected at the Y(4S) peak with the BABAR detector at PEP-II. The following branching fractions have been measured: BR(B+ --> phi K+) = (7.7^{+1.6}_{-1.4} +- 0.8)*10^{-6}, BR(B0 --> phi K0) = (8.1^{+3.1}_{-2.5} +- 0.8)*10^{-6}, BR(B+ --> phi K*+) = (9.7^{+4.2}_{-3.4} +- 1.7)*10^{-6}, BR(B0 --> phi K*0) = (8.7^{+2.5}_{-2.1} +- 1.1)*10^{-6}, BR(B+--> omega pi+) = (6.6^{+2.1}_{-1.8} +- 0.7)*10^{-6}, BR(B --> eta K^*0) = (19.8^{+6.5}_{-5.6} +-1.7)*10^{-6}, where the first error is statistical and the second systematic. For several other modes we report upper limits on their branching fractions; for example for the following flavor-changing neutral current decays, BR(B--> K l+ l-) < 0.6*10^{-6}, BR(B--> K* l+ l-) < 2.5*10^{-6}, at 90% Confidence Level (C.L.).