A Measurement of the KL Charge Asymmetry

TL;DR

This paper reports a highly precise measurement of the charge asymmetry in neutral kaon decays, improving the accuracy over previous results and testing fundamental symmetries in particle physics.

Contribution

It provides the most precise measurement to date of the KL charge asymmetry, enhancing constraints on CPT violation and $ riangle S = riangle Q$ symmetry in the neutral kaon system.

Findings

Measured $ ext{δ}_L$ with 2.4 times improved precision

Results agree with previous measurements

Stricter limits on CPT and $ riangle S = riangle Q$ violation

Abstract

We present a measurement of the charge asymmetry $\delta_L$ in the mode $K_L \to \pi^{\pm}e^{\mp}\nu$ based on 298 million analyzed decays. We measure a value of $\delta_L = (3322 \pm 58(stat) \pm 47(sys))\cdot 10^{-6}$, in good agreement with previous measurements and 2.4 times more precise than the current best published result. The result is used to place more stringent limits on CPT and $\Delta S = \Delta Q$ violation in the neutral kaon system.