Measurements of KL Branching Fractions and the CP Violation Parameter |eta+-|

TL;DR

This paper reports new measurements of the main decay modes of the KL meson and the CP violation parameter |eta+-|, using Fermilab data, highlighting some discrepancies with previous measurements.

Contribution

First measurements of several KL decay branching fractions and CP violation parameter |eta+-| using Fermilab data, with some results differing from prior averages.

Findings

Measured branching fractions of six KL decay modes.

Determined CP violation parameter |eta+-| = (2.228 +- 0.010)E-3.

Several results differ from previous measurements.

Abstract

We present new measurements of the six largest branching fractions of the KL using data collected in 1997 by the KTeV experiment (E832) at Fermilab. The results are B(KL -> pi e nu) = 0.4067 +- 0.0011 B(KL -> pi mu nu) = 0.2701 +- 0.0009 B(KL -> pi+ pi- pi0) = 0.1252 +- 0.0007 B(KL -> pi0 pi0 pi0) = 0.1945 +- 0.0018 B(KL -> pi+ pi-) = (1.975 +- 0.012)E-3, and B(KL -> pi0 pi0) = (0.865 +- 0.010)E-3, where statistical and systematic errors have been summed in quadrature. We also determine the CP violation parameter |eta+-| to be (2.228 +- 0.010)E-3. Several of these results are not in good agreement with averages of previous measurements.