The dynamics of SU(N) gauge theories, especially for N = 3, in a small
C-periodic box are investigated. We identify the fields that mimimize
the energy - the torons - and determine which of these ''classical''
vacua are stable quantum mechanically. The stable torons break cubic s
ymmetry, which has interesting consequences on the spectrum. At any of
the stable torons there are also quartic modes. Since all C-periodic
boundary conditions are gauge-equivalent, we choose a convenient versi
on, for which the quartic modes are constant modes, and compute the ef
fective hamiltonian to one loop in perturbation theory.