  It is commonly accepted that in hadronic or nuclear collisions at extremely
high energies the shortest scales are explored. At the classical level, this
property of the interaction is closely related to the Lorentz contraction of
the fields of colliding particles which provides instantaneous switching the
interaction on. I argue that the underlying quantum dynamics should be confined
to within the light wedge of the two-dimensional plane where the first
interaction takes place and suggest to include this property as the boundary
condition for the quantum field theory which describes the collision process.
Connection between the type of inclusive process and the temporal order of its
dynamical evolution is discussed. The one-particle states and propagators of
the perturbation theory for the scalar and fermion fields are found.
