2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/52824We propose a reduced form of spectral boundary conditions for holding fermions in the bag in a chiral invariant way. Our boundary conditions do not depend on time and allow Hamiltonian treatment of the system. They are suited for studies of chiral phenomena both in Minkowski and Euclidean spaces.LaTeX, 9 pages, Talk given at 13th International Seminar "Quarks-2004", Pushkinskie Gory, May 2004High Energy Physics - Theorytext