  The effect of quantum corrections to a conformally invariant field theory for
a self-interacting scalar field on a curved manifold with boundary is
considered. The analysis is most easily performed in a space of constant
curvature the boundary of which is characterised by constant extrinsic
curvature. An extension of the spherical formulation in the presence of a
boundary is attained through use of the method of images. Contrary to the
consolidated vanishing effect in maximally symmetric space-times the
contribution of the massless "tadpole" diagram no longer vanishes in
dimensional regularisation. As a result, conformal invariance is broken due to
boundary-related vacuum contributions. The evaluation of one-loop contributions
to the two-point function suggests an extension, in the presence of matter
couplings, of the simultaneous volume and boundary renormalisation in the
effective action.
