Measurements of Branching Fractions and CP-violating Asymmetries in B0->pi+ pi-, K+ pi-, K+ K- Decays

TL;DR

This paper reports measurements of branching fractions and CP asymmetries in B0 decays to pi+ pi-, K+ pi-, and K+ K- final states using a large data sample, providing insights into CP violation in the B meson system.

Contribution

First measurement of CP-violating parameters in B0 decays to pi+ pi- and K+ pi- with a large data set, improving understanding of CP violation.

Findings

Measured branching fractions for B0-->pi+pi- and B0-->K+pi-

Observed direct CP asymmetry in B0-->K+pi- decays

Provided constraints on CP-violating parameters in B0 decays

Abstract

We present measurements of branching fractions and CP-violating asymmetries for neutral B meson decays to two-body final states of charged pions and kaons based on a sample of about 88 million Y(4S)-->BB decays. From a time-independent fit we measure the charge-averaged branching fractions B(B0-->pi+pi-) = (4.7 +/- 0.6 +/- 0.2) x 10^-6, B(B0-->K+pi-) = (17.9 +/- 0.9 +/- 0.7) x 10^-6, and the direct CP-violating charge asymmetry A(Kpi) = -0.102 +/- 0.050 +/- 0.016; [-0.188,-0.016], where the ranges in square brackets indicate the 90% confidence intervals. From a time-dependent fit we measure the B0-->pi+pi- CP-violating parameters Spipi = 0.02 +/- 0.34 +/- 0.05; [-0.54,+0.58] and Cpipi = -0.30 +/- 0.25 +/- 0.04; [-0.72,+0.12].