Kaon Experiments

TL;DR

This paper reviews the history and progress of kaon experiments, highlighting how high-precision measurements supported the Kobayashi-Maskawa model and how recent rare decay studies aim to uncover new physics beyond the Standard Model.

Contribution

It summarizes advancements in kaon experimental techniques and their implications for understanding CP violation and searching for new physics.

Findings

High-precision experiments supported the Kobayashi-Maskawa model.

Rare decay experiments are probing for new physics beyond the Standard Model.

Techniques have been developed to improve sensitivity and background suppression.

Abstract

After $CP$ violation was discovered in the $K_L \to \pi^+\pi^-$ decay, many theories were proposed to explain it, and the Kobayashi-Maskawa model and the Superweak model lasted for many years as strong candidates. High-precision kaon experiments with many new techniques and improvements rejected the Superweak model and supported the Kobayashi-Maskawa model in 1990's. After then, rare kaon decay experiments are studying $K_L \to \pi^0\nu \overline{\nu}$ decays to search for $CP$ violation caused by new physics beyond the Standard Model. Various techniques have been developed to increase the sensitivity and to suppress backgrounds.