CP Violation in Kaon Decays (II)

TL;DR

This paper reviews 50 years of progress in kaon physics, highlighting experimental advancements in measuring CP violation and rare decays, and discusses ongoing searches for new physics beyond the standard model.

Contribution

It provides a comprehensive overview of experimental improvements and methodologies in kaon decay measurements, emphasizing progress in detecting rare decays and CP violation.

Findings

Significant increase in KL->pi+pi- event detection

Experimental proof linking CP violation to CKM matrix phase

Ongoing efforts to detect K->pi nu nu-bar decays as new physics probes

Abstract

Major progress has been made in kaon physics in the past 50 years. The number of KL->pi+pi- events has increased by 6 orders of magnitude, and the observed CP violation was experimentally proven to be caused by a complex phase in the CKM matrix. Recent kaon experiments are now searching for new physics beyond the standard model with the K->pi nu nu-bar decays. The branching ratio of K->pi nu nu-bar decays are 7-8 orders of magnitude smaller than the branching ratio of KL->pi+ pi-. This paper reviews the progress of kaon experiments in the US and Japan, and how the 6-7 orders of magnitude improvements were possible in the past 50 years.