We have studied the null-plane hamiltonian structure of the free Yang-Mills fields and the scalar chromodynamics (SQCD4). Following the Dirac’s procedure for constrained systems we have performed a detailed analysis of the constraint structure of both models and we give the generalized Dirac brackets for the physical variables. In the free Yang-Mills case, using the correspondence principle in ...

I prove that, in models with complementarities, some non-monotone comparative statics must select unstable equilibria; and, under additional regularity conditions, that monotone comparative statics selects stable equilibria. JEL Classification. C61, C62, C72, C73. Discussions with my advisers, Ilya Segal and Chris Shannon, were very important for this work. I am very grateful for their help. I ...

It is shown that quantum mechanical systems obtained from a heuristic path integral quantization of lagrangians of the form L = ∑ n 1 n! fn(q)q̇ n violate in general the correspondence principle, unless L is not more than quadratic in q̇. The field theoretic counterpart of this result and its consequence on models of interacting scalar and vector fields and particularly the electroweak interactio...