  In this work we investigate possible actions for antisymmetric two-tensor
field models subject to constraints that force the field to acquire a nonzero
vacuum expectation value, thereby spontaneously breaking Lorentz invariance. In
order to assure stability, we require that the associate Hamiltonian be bounded
from below. It is shown that this requirement rules out any quadratic action
constructed only from the antisymmetric tensor field. We then explicitly
construct a hybrid model consisting of the antisymmetric two-tensor field
together with a vector field, subject to constraints forcing nonzero
expectation values, that is stable in Minkowski space.
