Cosmological Coleman-Weinberg Potentials and Inflation
  We consider an additional fine-tuning problem which afflicts scalar-driven
models of inflation. The problem is that successful reheating requires the
inflaton be coupled to ordinary matter, and quantum fluctuations of this matter
induces Coleman-Weinberg potentials which are not Planck-suppressed. Unlike the
flat space case, these potentials depend upon a still-unknown, nonlocal
functional of the metric which reduces to the Hubble parameter for de Sitter.
Such a potential cannot be completely subtracted off by any local action. In a
simple model we numerically consider one possible subtraction scheme in which
the correction is locally subtracted at the beginning of inflation. For
fermions the effect is to make the universe approach de Sitter with a smaller
Hubble parameter. For gauge bosons the effect is to make inflation end almost
instantly unless the gauge charge is unacceptably small.
