  Long-lived colored particles with masses m > 200 GeV are allowed by current
accelerator searches, and are predicted by a number of scenarios for physics
beyond the standard model. We argue that such "heavy partons'' effectively have
a geometrical cross section (of order 10 mb) for annihilation at temperatures
below the QCD deconfinement transition. The annihilation process involves the
formation of an intermediate bound state of two heavy partons with large
orbital angular momentum. The bound state subsequently decays by losing energy
and angular momentum to photon or pion emission, followed by annihilation of
the heavy partons. This decay occurs before nucleosynthesis for m < 10^{11} GeV
for electrically charged partons and m < TeV for electrically neutral partons.
This implies that heavy parton lifetimes as long as 10^{14} sec are allowed
even for heavy partons with m ~ TeV decaying to photons or hadrons with
significant branching fraction.
