Colour: A Computer Program for QCD Colour Factor Calculations

A computer program for evaluating colour factors of QCD Feynman diagrams is presented, and illustrative examples on how to use the program to calculate non trivial colour factors are given. The program and the discussion in this paper is based on a diagrammatic approach to colour factors.Comment: 12 pages, Latex and postscript figures in an uuencode packag

Electroweak corrections to decays involving a charged Higgs boson

We present complete one-loop radiative corrections to the decay rate of a top quark into a charged Higgs boson and a bottom quark, and for the decay of a charged Higgs boson into leptons. The results are discussed in the framework of the two Higgs boson extension of the Standard Model suggested by supersymmetry. The effect of electroweak corrections after exclusion of universal corrections $\Delta r$ is found to decrease the partial width of the top quark typically by 5%.Comment: 16 pages plus 11 figures available from the author upon request, latex, Alberta Thy-29-9