  We study the zero temperature random field Ising model as a model for noise
and avalanches in hysteretic systems. Tuning the amount of disorder in the
system, we find an ordinary critical point with avalanches on all length
scales. Using a mapping to the pure Ising model, we Borel sum the $6-\epsilon$
expansion to $O(\epsilon^5)$ for the correlation length exponent. We sketch a
new method for directly calculating avalanche exponents, which we perform to
$O(\epsilon)$. Numerical exponents in 3, 4, and 5 dimensions are in good
agreement with the analytical predictions.
