Phenomenology of sub-GeV Dark Matter - Monte-Carlo based developments and Search Strategies

Abstract

The nature of dark matter is one of the most exciting questions of fundamental physics. In terms of a particle physics model the mass spectrum for possible dark matter candidates is huge. Extensive experimental programs seek to unveil the microscopic physics governing dark matter. While indirect and direct detection as well as collider searches have excluded a large class of dark matter models at the weak scale, the region below the GeV scale is relatively unexplored by these experiments. Therefore, it is particularly interesting to study the phenomenology of sub-GeV dark matter. One of the leading constraints in the MeV to GeV range is expected to be set by indirect detection. However, a theoretical description of dark matter annihilation processes into Standard Model quarks is missing yet. In a Monte-Carlo based implementation in Herwig, we provide, for the first time, a modeling of these annihilations for dark matter models with vector mediators. This allows for a comprehensive study of sub-GeV dark matter annihilations in indirect detection searches. In the sub-MeV mass range, low energy experiments and astrophysical as well as cosmological ob- servations can set constraints on dark matter couplings to the Standard Model. If the dark matter candidate does not couple to the Standard Model Higgs, standard collider searches are not able to probe dark matter masses at the order of a few eV. We sytematically study a wealth of constraints on scalar and pseudoscalar dark matter candidates over a large range of dark matter masses. In addition, we introduce a novel search strategy at the LHC that extends the reach of complementary searches for light dark matter candidates.