Study of CP-violating asymmetries in B-->pi^+/-pi^-/+, K^+/-pi^-+ decays

TL;DR

This paper reports measurements of CP-violating asymmetries in B meson decays to pi pi and K pi final states, using data from the BABAR detector, providing insights into matter-antimatter asymmetry.

Contribution

First measurement of time-dependent CP asymmetries in B to pi pi decays and an updated charge asymmetry in B to K pi decays using a large data sample.

Findings

Measured S_pipi = 0.03 with large uncertainties

Measured C_pipi = -0.25 with large uncertainties

Measured A_Kpi = -0.07 with uncertainties

Abstract

We present a preliminary measurement of the time-dependent CP-violating asymmetry parameters S_pipi and C_pipi in neutral B decays to the pi^+/-pi^-/+ CP eigenstate, and an updated preliminary measurement of the charge asymmetry A_Kpi in B --> K^+/-pi^-/+ decays. Event yields and $\CP$-violation parameters are determined simultaneously from a multidimensional unbinned maximum likelihood fit. In a data sample consisting of approximately 33 million Upsilon(4S)--)B-anti-B decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory, we find 65^{+12}_{-11} pi^+/-pi^-/+ and 217+/-18 K^+/-pi^-/+ candidates and measure S_pipi = 0.03^{+0.53}_{-0.56}+/-0.11, C_pipi = -0.25^{+0.45}_{-0.47}+/-0.14, and A_Kpi = -0.07+/-0.08+/-0.02, where the first error is statistical and the second is systematic.