EXPERIMENTAL LIMITS ON THE PHOTON MASS AND COSMIC MAGNETIC VECTOR POTENTIAL

A novel experimental approach based on a toroid Cavendish balance is u sed to evaluate the product of photon mass squared and the ambient cos mic magnetic vector potential A. The method is based on the energy den sity of the vector potential in the presence of photon mass, not on me asurement of the magnetic field. The experiment discloses A mu(gamma)( 2) < 2 X 10(-9) T m/m(2), with mu(gamma)(-1) as the characteristic len gth associated with photon mass. Consequently, if the ambient magnetic vector potential is A approximate to 10(12) T m due to cluster level fields, mu(gamma)(-1) > 1 x 10(10) m. If we conservatively use galacti c fields prior to a reversal, then mu(gamma)(-1) > 1 x 10(9) m, a figu re still superior to that derived from the Jovian magnetic field.