Measurements of Branching Fractions and Time-Dependent CP-Violating Asymmetries in B to eta' K Decays

TL;DR

This paper reports precise measurements of branching fractions and CP-violation parameters in B to eta' K decays using a large data sample, providing insights into CP violation and testing the Standard Model.

Contribution

First measurement of time-dependent CP asymmetries in B to eta' K decays with a large dataset, improving understanding of CP violation in these processes.

Findings

Branching fractions measured at approximately 69 x 10^-6 and 67 x 10^-6.

CP-violation parameters S and C determined with statistical and systematic uncertainties.

Results consistent with Standard Model predictions.

Abstract

We present measurements of the B -> eta' K branching fractions;for B+ -> eta' K+ we measure also the time-integrated charge asymmetry Ach, and for B0 -> eta' K0S the time dependent CP-violation parameters S and C. The data sample corresponds to 232 million B Bbar pairs produced by e+ e- annihilation at the Upsilon(4S). The results are BF(B+ -> eta' K+) = (68.9 +- 2.0 +- 3.2) * 10^-6, BF(B0 -> eta' K0) = (67.4 +- 3.3 +- 3.2) * 10^-6, Ach = 0.033 +- 0.028 +- 0.005, S=0.30 +- 0.14 +- 0.02, C=-0.21 +- 0.10 +- 0.02, where the first error is statistical and the second systematic.