Dimensional regularisation and gauge theories

Dimensional regularisation is formulated without using the assumption that f d(^D)k(k(^2))(^n) = 0. Alternative definitions of ϵ(_kλµv) and γ(^5) are also considered. In the reformulated scheme, quadratic divergences are present, in general, in the scalar and gauge boson self-energies, and remain unregularised. The possible cancellation of such divergences is investigated. Phenomenological aspects of unified gauge theories are studied.