Impact of semi-annihilations on dark matter phenomenology - an example of Z_N symmetric scalar dark matter

We study the impact of semi-annihilations x(i)x(j) <-> x(k)X and dark matter conversion x(i)x(j) <-> x(k)x(l), where x(i) is any dark matter and X is any standard model particle, on dark matter phenomenology. We formulate minimal scalar dark matter models with an extra doublet and a complex singlet that predict non-trivial dark matter phenomenology with semi-annihilation processes for different discrete Abelian symmetries Z(N), N > 2. We implement two such example models with Z(3) and Z(4) symmetry in micrOMEGAs and work out their phenomenology. We show that both semi-annihilations and dark matter conversion significantly modify the dark matter relic abundance in this type of models. In the Z(4) model, there are two stable neutral particles and therefore multi-component dark matter. We also study the possibility of dark matter direct detection in XENON100 in those models.