Revisiting Big-Bang Nucleosynthesis Constraints on Dark-Matter
  Annihilation
  We study the effects of dark-matter annihilation during the epoch of big-bang
nucleosynthesis on the primordial abundances of light elements. We improve the
calculation of the light-element abundances by taking into account the effects
of anti-nucleons emitted by the annihilation of dark matter and the
interconversion reactions of neutron and proton at inelastic scatterings of
energetic nucleons. Comparing the theoretical prediction of the primordial
light-element abundances with the latest observational constraints, we derive
upper bounds on the dark-matter pair-annihilation cross section. Implication to
some of particle-physics models are also discussed.
