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Relic Abundance due to Cosmic Pair Annihilation

Sh. Matsumoto·M. Yoshimura
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Abstract

Pair annihilation of heavy stable particles that occurs in the early universe is reconsidered including the off-shell effect not properly taken into account by the conventional Boltzmann equation approach. Our new calculation of the time evolution shows that the off-shell effect prolongs the freeze-out, always with a larger final relic abundance. The final yield (number density/temperature^3) is insensitive to the effective coupling for the annihilation and of order (10^{- 8}\times (M/1 GeV)^{1/3}), with $M$ the heavy particle mass, if the coupling is not too small.

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Sh. Matsumoto, M. Yoshimura. 1998-09-30. Relic Abundance due to Cosmic Pair Annihilation. https://arxiv.org/abs/hep-ph/9809585

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