Measurements of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Charmless Two-Body States Containing a K0

TL;DR

This paper reports measurements of branching fractions and CP asymmetries in B meson decays to charmless two-body states with a K0, using data from the BaBar detector, providing insights into CP violation and rare decay processes.

Contribution

The study provides the first precise measurements of branching fractions and CP asymmetries in specific B meson decay channels involving K0, expanding understanding of CP violation in charmless B decays.

Findings

Measured branching fractions for B+ and B0 decays to K0 and pions.

Established upper limits for rare decay modes involving K0 and K0bar.

Found CP asymmetries consistent with Standard Model expectations.

Abstract

We present measurements of branching fractions and \CP-violating asymmetries in decays of $B$ mesons to two-body final states containing a \Kz. The results are based on a data sample of approximately 88 million \upsbb decays collected with the \babar detector at the \pep2 asymmetric-energy $B$ Factory at SLAC. We measure $\BR(\Bp\to\Kz\pip) = (22.3 \pm 1.7 \pm 1.1)\times 10^{-6}$, $\BR(\Bz\to\Kz\piz) = (11.4\pm 1.7\pm 0.8)\times 10^{-6}$, $\BR(\Bp\to\Kzb\Kp) < 2.5\times 10^{-6}$, and $\BR(\Bz\to\KzKzb) < 1.8\times 10^{-6}$, where the first uncertainty is statistical and the second is systematic, and the upper limits are at the 90% confidence level. In addition, the following \CP-violating asymmetries have been measured: ${\cal A}_{CP}(\Bp\to\Kz\pip) = -0.05 \pm 0.08 \pm 0.01$ and ${\cal A}_{CP}(\Bz\to\Kz\piz) = 0.03 \pm 0.36\pm 0.11$.