  We consider a disordered system of gapless fermions interacting with a
singular transverse (2+1)-dimensional gauge-field. We study quantum corrections
to fermion conductivity and show that they are very different from those in a
Fermi liquid with non-singular interactions. In particular, the
weak-localization effect is suppressed by magnetic field fluctuations. We argue
that these fluctuations can be considered static at time scales of fermionic
diffusion. By inducing fluxes through diffusive loops that contribute to weak
localization, they dephase via the Aharonov-Bohm effect. It is shown that while
the flux-flux correlator due to thermal fluctuations of magnetic field is
proportional to the area enclosed by the loop, the correlator due to quantum
fluctuations is proportional to the perimeter of the loop. The possibility of
dephasing due to these quasistatic configurations and the corresponding rates
are discussed. We also study interaction induced effects and show that
perturbation theory contains infrared divergent terms originating from
unscreened magnetic interactions. These singular (Hartree) terms are related to
scattering of a fermion off of the static potential created by the other
fermions. We show that due to singular small-angle scattering, the
corresponding contributions to the density of states and conductivity are very
large and positive indicating that the fermion-gauge system remains metallic at
low temperatures.
