TACHYONS AND PREFERRED FRAMES

Quantum field theory of spacelike particles is investigated in the fra mework of an absolute causality scheme preserving Lorentz symmetry. It is related to an appropriate choice of the synchronization procedure (definition of time). In this formulation existence of field excitatio ns (tachyons) distinguishes an inertial frame (privileged frame of ref erence) via spontaneous breaking of the so-called synchronization grou p. In this scheme the relativity principle is broken but Lorentz symme try is exactly preserved in agreement with local properties of the obs erved world. It is shown that tachyons are associated with unitary orb its of Poincare mappings induced from the SO(2) little group instead o f the SO(2, 1) one. Therefore the corresponding elementary states are labeled by helicity. The cases of the helicity lambda = 0 and lambda = +/-1/2 are investigated in detail and a corresponding consistent fiel d theory is proposed. In particular, it is shown that the Dirac-like e quation proposed by Chodos et al.,(1) inconsistent in the standard for mulation of QFT, can be consistently quantized in the presented framew ork. This allows us to treat more seriously the possibility that neutr inos might be fermionic tachyons, as is suggested by experimental data about neutrino masses.(2-4)