Measurements of sin 2β in B decays

A primary objective of particle physics since the 1964 discovery of CP non-conservation in weak decays has been the understanding of the effect as a natural feature of the structure of the weak interaction. A clue was offered in 1973 by Kobayashi and Maskawa in anticipation of the discovery of a third fermion family. With three families the unitary transformation to the weak isospin basis of the left-handed fermions has four parameters, including one complex phase that breaks the CP symmetry of the flavor-changing transitions. In the Wolfenstein parameterization the CKM matrix V is