Lessons from Recent Measurements of CP Violation

We discuss various implications of recent experimental results concerning CP violation and mixing in K → ππ, B → ψKS , D → Kπ and D → KK decays. 1. Progress in Experiments The study of CP violation is entering a new era. For a long period only a single CP violating observable has been measured [1]: |εK | = 2.27× 10. (1.1) In the near future, however, we will learn the values of CP asymmetries in various B decays [2, 3, 4]. Then we will be able to test the Standard Model (SM) picture of CP violation [5]. Moreover, already at present we know more about CP violation than eq. (1.1). In particular, in the last year, the following new measurements have been made: (i) Direct CP violation in K → ππ decays has been observed. The two latest measurements give: ε ε = { (28.0± 4.1)× 10 KTeV [6], (14.0± 4.3)× 10 NA48 [7], (1.2) which, in combination with previous results [8, 9, 10], give a world average of ε ε = (1.93± 0.24)× 10. (1.3) (ii) CP violation inB → ψKS has been searched for. The three most precise measurements give: