QUANTUM CORRECTIONS TO THE CONDUCTIVITY OF FERMION GAUGE-FIELD MODELS- APPLICATION TO THE HALF-FILLED LANDAU-LEVEL

We calculate the Altshuler-Aronov-type quantum correction to the condu ctivity of 2D charge carriers in a random potential (or random magneti c field) coupled to a transverse gauge held. The gauge fields consider ed may simulate the effect of the Coulomb interaction for the fraction al quantum Hall state at half filling and for the t-J model of high-T- c superconducting compounds. We find an unusually large quantum correc tion varying linearly or quadratically with the logarithm of temperatu re, in different temperature regimes. The magnitude of the correction is in good agreement with recent experimental observations at half fil ling of the Landau level.