The wedge form of relativistic dynamics
  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. 
A.Makhlin