EPJ

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EPJ C - Particles and Fields
Particles and Fields
Eur. Phys. J. C 9, 319-333
DOI 10.1007/s100529900029

Flavour dynamics with general scalar fields

W. Bernreuther1 - O. Nachtmann2

1 Institut für Theoretische Physik, RWTH Aachen, D-52056 Aachen, Germany
2 Institut für Theoretische Physik, Universität Heidelberg, D-69120 Heidelberg, Germany

Received: 18 December 1998 / Published online: 22 March 1999

Abstract
We consider a spontaneously broken gauge theory based on the standard model (SM) group $G = SU(2)\times U(1)$ with scalar fields that carry arbitrary representations of G, and we investigate some general properties of the charged and neutral current involving these fields. In particular we derive the conditions for having real or complex couplings of the Z boson to two different neutral or charged scalar fields, and for the existence of CP-violating Z-scalar-scalar couplings. Moreover, we study models with the same fermion content as in the SM, with one SU(2) Higgs singlet, and an arbitrary number of Higgs doublets. We show that the structure of the Z-Higgs boson and of the Yukawa couplings in these models can be such that CP-violating $Zb{\bar b}G$ form factors which conserve chirality are induced at the one-loop level.

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