SEARCH FOR NEARLY MASSLESS, WEAKLY COUPLED PARTICLES BY OPTICAL TECHNIQUES

We have searched for light scalar and/or pseudoscalar particles that couple to two photons by studying the propagation of a laser beam (lambda=514 nm) through a transverse magnetic field. A limit of 3.5 X 10(-10) rad was set on a possible optical rotation of the beam polarization for an effective path length of 2.2 km in a 3.25 T magnetic field. We find that the coupling g(alphagammagamma) < 3.6 X 10(-7) GeV-1 at the 95% confidence level, provided m(a) < 10(-3) eV. Similar limits can be set from the absence of ellipticity in the transmitted beam. We also searched for photon regeneration in a magnetic field and found the limit g(alphagammagamma) < 6.7 X 10(-7) GeV-1 for the same range of particle mass.