  Density and temperature conditions in the solar core suggest that the
microscopic diffusion of electrons and ions could be nonstandard:
  Diffusion and friction coefficients are energy dependent, collisions are not
two-body processes and retain memory beyond the single scattering event.
  A direct consequence of nonstandard diffusion is that the equilibrium energy
distribution of particles departs from the Maxwellian one (tails goes to zero
more slowly or faster than exponentially) modifying the reaction rates.
  This effect is qualitatively different from temperature and/or composition
modification: Small changes in the number of particles in the distribution
tails can strongly modify the rates without affecting bulk properties, such as
the sound speed or hydrostatic equilibrium, which depend on the mean values
from the distribution.
  This mechanism can considerably increase the range of predictions for the
neutrino fluxes allowed by the current experimental values (cross sections and
solar properties) and can be used to reduce the discrepancy between these
predictions and the solar neutrino experiments.
