Measurement of CP-violating asymmetries in B0 decays to CP eigenstates

TL;DR

This paper reports a measurement of CP-violating asymmetries in neutral B meson decays to CP eigenstates, using data from the BABAR detector, with results consistent with Standard Model predictions within uncertainties.

Contribution

First measurement of time-dependent CP asymmetries in B0 decays to CP eigenstates using the BABAR detector at SLAC.

Findings

Measured sin2beta = 0.34 ± 0.20 (stat) ± 0.05 (syst)

Used 23 million B-anti-B decays from Upsilon(4S)

Confirmed consistency with Standard Model within errors

Abstract

We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23 million Upsilon(4S)-->B-anti-B decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events where one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta=0.34 +/- 0.20 (stat) +/- 0.05 (syst).