Possible consequences of the K20 → π+ + π− decay (CP violation and other interpretations)

In a recent paper, Christenson, Cronin, Fitch and Turlay (CCFT) report the observation of the decay of the long-lived component of a K° beam into ð +ð · They obtain a branching ratio of (2 ± 0.4) 10 over other charged decay modes. We will discuss here the possible interpretations of this result. Since these modify in one way or another our present picture of physics, some independent confirmation of the CCFT experiment is necessary· In these lectures I will discuss some problems connected with this experiment, possible theoretical interpretations, and their experimental consequences· The first chapter will serve as an introductory review of the main decay modes of neutral K mesons; in the others I will speak of the matter of interest.