Three-dimensional massive gauge theories

Three-dimensional Yang-Mills and gravity theories augmented by gauge-invariant-mass terms are analyzed. These topologically nontrivial additions profoundly alter the particle content of the models and lead to quantization of a dimensionless mass-coupling constant ratio. The vector field excitations become massive, with spin 1 [rather than massless with spin 0] and the mass provides an infrared cutoff. The graviton acquires mass, mediates finite-range interactions, and has spin 2 [rather than being absent altogether]; although its mass term is of third derivative order, there are no ghosts or acausalities