BBN constraints on the annihilation of MeV-scale dark matter
  Thermal dark matter at the MeV scale faces stringent bounds from a variety of
cosmological probes. Here we perform a detailed evaluation of BBN bounds on the
annihilation cross section of dark matter with a mass $1\,\text{MeV} \lesssim
m_\chi \lesssim 1\,\text{GeV}$. For $p-wave suppressed annihilations,
constraints from BBN turn out to be significantly stronger than the ones from
CMB observations, and are competitive with the strongest bounds from other
indirect searches. We furthermore update the lower bound from BBN on the mass
of thermal dark matter using improved determinations of primordial abundances.
While being of similar strength as the corresponding bound from CMB, it is
significantly more robust to changes in the particle physics model.
