Resonant Interactions of Dark Matter Particles Using Effective Field Theory

by Evan Johnson (Ohio State University)

Monday 30 Sept 2019, 14:00 → 15:00 Europe/Berlin

The particle nature of dark matter is a compelling mystery in physics. Weakly interacting massive particles (WIMPs) are a well motivated hypothesis for the dark matter particle, and supersymmetric (SUSY) theories contain natural candidates. WIMP annihilation into Standard Model particles provides key constraints on properties of the dark matter and therefore on the large SUSY parameter space. Resonances associated with bound states of WIMPs can be important, because annihilation of WIMPs in bound states can increase the overall annihilation rate, thus possibly strengthening existing constraints on dark matter models. Orders-of-magnitude ``Sommerfeld enhancements'' to annihilation rates can arise near a sequence of TeV-scale critical values of the WIMP mass where there is a zero-energy S-wave resonance at the WIMP-pair scattering threshold. Close to these critical values, the low-energy behavior of the WIMPs can be described by a zero-range effective field theory (ZREFT) in which they interact nonperturbatively through contact interactions and through Coulomb interactions. ZREFT at leading order gives an accurate analytic description of low-energy WIMP-WIMP scattering, inclusive WIMP-pair annihilation, and a WIMP-pair bound state. ZREFT can also be applied to partial annihilation rates, such as the Sommerfeld enhancement of the annihilation rate of WIMP pairs into monochromatic photons, which is extremely important for indirect detection searches for dark matter annihilating in our Milky Way galaxy.