New Tests for the Invariance of the Vacuum State Under the Lorentz Group

Abstract

We assume that Lorentz invariance is broken in the simplest possible way by the existence of a constant vector field ${\lambda }^{\mu }$ which is coupled as if it were an ordinary quantized field. The presence of ${\lambda }^{\mu }$ could explain the decay of ${K_2}^0$ into ${\pi }^{+}{\pi }^{-}$ and avoid the difficulties which accompany a similar theory put forward by Bell and Perring. If the coupling is through axial- as well as polar-vector terms a new set of low-energy experiments will serve to elucidate the form of ${\lambda }^{\mu }$ in much greater detail than is possible by using ${K_2}^0$. Present experimental limits are discussed and we conclude that their improvement by several orders of magnitude is feasible.