Quest for Faster-Than-Light Particles

Abstract

An experimental search for the existence of particles that propagate with velocities that are always greater than the velocity of light in a vacuum has been performed. Subject to some assumptions regarding the behavior of such particles, it is found that the photoproduction cross section for such particles in lead is less than 3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}30}$ ${\mathrm{cm}}^{2}$. This upper limit does not depend strongly on the "rest mass" of the particles and is approximately the same for faster-than-light particles of any "rest mass." This search was sensitive to particles having charges between 0.1 and 2 electron charges.