Castrillón López, MarcoMuñoz Masqué, JaimeRatiu, T.2023-06-202023-06-202003-090926-224510.1016/S0926-2245(03)00016-0https://hdl.handle.net/20.500.14352/50861Given 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 degreeengjournal articlehttp://www.sciencedirect.com/science/article/pii/S0926224503000160http://www.sciencedirect.com/restricted access514.7Characteristic classesConnections on a principal bundleEuler–Lagrange equationsGauge invarianceInfinitesimal symmetriesJet bundlesLagrangiansLie algebra representationsWeil polynomialsGeometría diferencial1204.04 Geometría Diferencial