The Relic Abundance of Long-lived Heavy Colored Particles

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.