Flavour Dynamics & CP Violation in the SM*: A Tale in Five Parts of Great Successes, Little Understanding -- and Promise for the Future!

Abstract

Our knowledge of flavour dynamics has undergone a `quantum jump' since just before the turn of the millenium: direct \cp violation has been firmly {\em established} in $K_L \to ππ$ decays in 1999; the first \cp asymmetry outside $K_L$ decays has been discovered in 2001 in $B_d \to ψK_S$, followed by $B_d \to π^+π^-$ and $B \to K^{\pm}π^{\mp}$, the latter establishing direct \cp violation also in the beauty sector. Furthermore CKM dynamics allows a description of \cp insensitive and sensitive $B$, $K$ and $D$ transitions that is impressively consistent also on the quantitative level. Theories of flavour dynamics that could serve as {\em alternatives} to CKM have been ruled out. Yet these novel successes of the Standard Model (SM) do not invalidate any of the theoretical arguments for the incompleteness of the SM. In addition we have also more direct evidence for New Physics, namely neutrino oscillations, the observed baryon number of the Universe, dark matter and dark energy. While the New Physics anticipated at the TeV scale is not likely to shed any light on the SM's mysteries of flavour, detailed and comprehensive studies of heavy flavour transitions will be essential in diagnosing salient features of that New Physics. Strategic principles for such studies will be outlined.