Propagator, tree-level unitarity and effective nonrelativistic potential for three-dimensional higher-derivative gravity augmented by a gravitational Chern–Simons term

An algorithm for computing the propagator for three-dimensional quadratic gravity with a gravitational Chern–Simons term, based on an extension of the three-dimensional Barnes–Rivers operators, is proposed. A systematic study of the tree-level unitarity of this theory is developed and its agreement with Newtonʹs law is investigated by computing the effective nonrelativistic potential.