%0 Journal Article %A Castrillón López, Marco %A Muñoz Masqué, Jaime %A Ratiu, T. %T Gauge invariance and variational trivial problems on the bundle of connections. %D 2003 %@ 0926-2245 %U https://hdl.handle.net/20.500.14352/50861 %X Given a principal bundle P→M we classify all first order Lagrangian densities on the bundle of connections associated to P that are invariant under the Lie algebra of infinitesimal automorphisms. These are shown to be variationally trivial and to give constant actions that equal the characteristic numbers of P if dimM is even and zero if dimM is odd. In addition, we show that variationally trivial Lagrangians are characterized by the de Rham cohomology of the base manifold M and the characteristic classes of P of arbitrary degree %~