  Although the whole conformal group $SO(4,2)$ can be considered as a symmetry
in a classical massless field theory, the subgroup of special conformal
transformations (SCT), usually related to transitions to uniformly accelerated
frames, causes vacuum radiation in the corresponding quantum field theory, in
analogy to the Fulling-Unruh effect. The spectrum of the outgoing particles can
be calculated exactly and proves to be a generalization of the Planckian one.
