X iv : h ep - t h / 99 07 05 5 v 2 1 0 Ju l 1 99 9 IPM / P - 99 / 037 hep - th / 9907055 Boundary Conditions as Dirac Constraints

In this article we show that boundary conditions can be treated as Lagrangian and Hamiltonian primary constraints. Using the Dirac method, we find that boundary conditions are equivalent to an infinite chain of second class constraints which is a new feature in the context of constrained systems. We discuss the Dirac brackets and the reduced phase space structure for different boundary conditions. We also show that in a quantized field theory subjected to the mixed boundary conditions, the field components are noncommutative.