  We study a simple sandpile model of active-absorbing state transitions in
which a particle can hop out of a site only if the number of particles at that
site is above a certain threshold. We show that the active phase has product
measure whereas nontrivial correlations are found numerically in the absorbing
phase. It is argued that the system relaxes to the latter phase slower than
exponentially. The critical behavior of this model is found to be different
from that of the other known universality classes.
