  We consider 2+1 gravity minimally coupled to a self-interacting scalar field.
The case in which the fall-off of the fields at infinity is slower than that of
a localized distribution of matter is analyzed. It is found that the asymptotic
symmetry group remains the same as in pure gravity (i.e., the conformal group).
The generators of the asymptotic symmetries, however, acquire a contribution
from the scalar field, but the algebra of the canonical generators possesses
the standard central extension. In this context, new massive black hole
solutions with a regular scalar field are found for a one-parameter family of
potentials. These black holes are continuously connected to the standard zero
mass black hole.
