  The sum-energy spectrum of electrons emitted in double-beta decay is a
well-known diagnostic for the nature of the physics which is responsible for
the decay. Three types of spectra are usually considered when these experiments
are analysed: one each for the standard two-neutrino decay, the neutrinoless
process and a scalar-emitting decay. It has recently been shown that two other
electron spectra can be possible for scalar-emitting modes, in addition to
these traditional three. One of these is softer than the Standard-Model
two-neutrino decay, while the other is intermediate between this and the usual
majoron-emitting spectrum. The models which predict these new spectra are
generically more natural than those which predict the traditional
majoron-emitting spectrum, in that they can accomodate the constraints
following from the steadily improving limits on neutrinoless decay without
requiring the fine-tuning that is endemic to the usual models. This article
reviews the properties of the physics which can produce the new kinds of
electron spectra. (Invited Talk presented to the Workshop on Double Beta Decay
and Related Topics, Trento Italy, April 1995.)
