Jul 26 – 30, 2010
Montpellier 2 University
Europe/Paris timezone

Semi-annihilation of Dark Matter

Jul 29, 2010, 11:25 AM
Salle des Actes (Montpellier 2 University)

Salle des Actes

Montpellier 2 University

Place Eugene Bataillon, 34095 Montpellier Cedex 5 FRANCE
Talk Dark Matter Candidates Parallel session : Dark Matter Candidates 1


Mr Francesco D'Eramo (Massachusetts Institute of Technology)


We show that the thermal relic abundance of dark matter can be affected by a new type of reaction: semi-annihilation. Semi-annihilation takes the schematic form X_i X_j -> X_k phi, where X_i are stable dark matter particles and phi is an unstable state. Such reactions are generically present when dark matter is composed of more than one species with "flavor" and/or "baryon" symmetries. We give a complete set of coupled Boltzmann equations in the presence of semi-annihilations, and study two toy models featuring this process. Semi-annihilation leads to non-trivial dark matter dynamics in the early universe, often dominating over ordinary annihilation in determining the relic abundance. This process also has important implications for indirect detection experiments, by enriching the final state spectrum from dark matter (semi-)annihilation in the Milky Way.

Primary authors

Mr Francesco D'Eramo (Massachusetts Institute of Technology) Jesse Thaler (Massachusetts Institute of Technology)

Presentation materials