Group field theories whose Feynman diagrams describe 3d gravity with a
varying configuration of Wilson loop observables and 3d gravity with volume
observables at each vertex are defined. The volume observables are created by
the usual spin network grasping operators which require the introduction of
vector fields on the group. We then use this to define group field theories
that give a previously defined spin foam model for fermion fields coupled to
gravity, and the simpler quenched approximation, by using tensor fields on the
group. The group field theory naturally includes the sum over fermionic loops
at each order of the perturbation theory.Comment: 13 pages, many figures, uses psfra
