We have shown that two of the most studied models of lineal gravities -- Liouville gravity and a ``string-inspired'' model exhibiting the main characteristic features of a black-hole solution -- can be formulated as gauge invariant theories of the Poincar\'e group. The gauge invariant couplings to matter (particles, scalar and spinor fields) and explicit solutions for some matter field configurations, are provided. It is shown that both the models, as well as the couplings to matter, can be obtained as suitable dimensional reductions of a 2+1-dimensional ISO(2,1) gauge invariant theory.
- Gauge theory for gravity
- lineal gravity