CP-violation with bosons

Abstract We formulate the conditions under which a purely bosonic theory (without fermions) containing neutral spin-0 particles and vector (gauge) bosons violates the CP -symmetry through the presence of CP -even and CP -odd operators in the lagrangian. This is done without reference to explicitly CP -violating scalar sector of extended standard models (SM) with two or more Higgs doublets. The lagrangian expressed in the mass basis of the spin-0 fields can, however, in certain circumstances be identified with a part of the CP -violating SM with two Higgs doublets. It is instructive to consider the manifestation of CP -violation in the mass basis since this leads directly to suggestions of genuine CP -signals.