Bohmian particle trajectories in relativistic bosonic quantum field   theory
  We study the de Broglie-Bohm interpretation of bosonic relativistic quantum mechanics and argue that the negative densities and superluminal velocities that appear in this interpretation do not lead to inconsistencies. After that, we study particle trajectories in bosonic quantum field theory. A new continuously changing hidden variable - the effectivity of a particle (a number between 0 and 1) - is postulated. This variable leads to a causal description of processes of particle creation and destruction. When the field enters one of nonoverlapping wave-functional packets with a definite number of particles, then the effectivity of the particles corresponding to this packet becomes equal to 1, while that of all other particles becomes equal to 0. 
H. Nikolic