The Chern-Simons Model with Boundary:. a Cohomological Approach

We consider a Chern-Simons model in the Landau gauge and introduce, following Symanzik ideas, a plane boundary which modifies the propagators. The BRS symmetry, restored at the classical level by a suitable choice of boundary counterterms becomes anomalous due to the lower dimensionality boundary breakings. The anomaly is recognized as the central charge of an algebra of conserved chiral currents defined on the boundary itself.