Bounds on the coupling of light pseudoscalars to nucleons from optical laser experiments

We find the following improved laboratory bounds on the coupling of light pseudoscalars to protons and neutrons: (Formula presented) and (Formula presented) The limit on (Formula presented) arises since a nonzero (Formula presented) would induce a coupling of the pseudoscalar to two photons, which is limited by experiments studying laser beam propagation in magnetic fields. Combining our bound on (Formula presented) with a recent analysis of Fischbach and Krause on two-pseudoscalar exchange potentials and experiments testing the equivalence principle, we obtain our limit on (Formula presented) © 1999 The American Physical Society.