A Symmetry Approach to CP Violation

Abstract

One of the greatest challenges for particle physics in the 1990's is understanding the broken symmetry of CP violation. It is now almost 30 years since the discovery in 1964 of the $K_{L} \rightarrow 2\pi$ decay. What has happened since? Why has there been no significant new experimental input in this long period? The original $K_{L} \rightarrow 2\pi$ decay experiment is described by two parameters $\epsilon$ and $\epsilon'$. Today $\epsilon \approx $ its 1964 value while $\epsilon'$ still consistent with zero, and there is no new evidence for CP violation outside the kaon system. Why is it so hard to find CP violation? How can B Physics Help? We present a symmetry approach to these questions.