CP Violation in Beauty Decays -- the Standard Model Paradigm of Large Effects

Abstract

The Standard Model contains a natural source for CP asymmetries in weak decays, which is described by the KM mechanism. Beyond ${ϵ}_K$ it generates only elusive manifestations of CP violation in {\em light-}quark systems. On the other hand it naturally leads to large asymmetries in certain non-leptonic beauty decays. In particular when $B^0-{\bar{B}}^0$ oscillations are involved, theoretical uncertainties in the hadronic matrix elements either drop out or can be controlled, and one predicts asymmetries well in excess of 10\% with high parametric reliability. It is briefly described how the KM triangle can be determined experimentally and then subjected to sensitive consistency tests. Any failure would constitute indirect, but unequivocal evidence for the intervention of New Physics; some examples are sketched. Any outcome of a comprehensive program of CP studies in $B$ decays -- short of technical failure -- will provide us with fundamental and unique insights into nature's design.

Comments: CERN-TH.7207/94, Invited lecture given at the VIII Rencontres de Physique de la Vallee d'Aoste, La Thuile, March 1994, 17 pages in LATEX, six figures available from author on request