  We present an effective field theory study of radiation and radiation
reaction effects for scalar and electromagnetic fields in general spacetime
dimensions. Our method unifies the treatment of outgoing radiation and its
reaction force within a single action principle. Central ingredients are the
field doubling method, which is the classical version of the closed time path
formalism and allows a treatment of non-conservative effects within an action,
action level matching of system and radiation zones, and the use of fields
which are adapted to the enhanced symmetries of each zone. New results include
compact expressions for radiative multipoles, radiation, and radiation reaction
effective action in any spacetime dimension. We emphasize dimension-dependent
features such as the difference between electric and magnetic multipoles in
higher dimensions and the temporal non-locality nature of the effective action
for odd spacetime dimensions, which is a reflection of indirect propagation
("tail effect") in the full theory. This work generalizes the method and
results developed for 4 dimensions in [arXiv:1305.6930], and prepares the way
for a treatment of the gravitational case.
