Discovery-HET Seminar: Jonathan Cornell

Speaker: Jonathan Cornell (McGill)

Title: Dark Matter Kinetic Decoupling and Small Scale Structure

Abstract: WIMP kinetic decoupling leads to a exponential cutoff of the matter power spectrum, corresponding to the size of smallest dark matter halo which can form in the early universe. In this talk, I will begin by presenting results of calculations of the halo cutoff mass for a generic WIMP whose interactions with standard model fermions can be described by effective operators. Taking into account constraints from direct detection and collider searches, we show that this cutoff mass can be required to be quite small, on the order of an earth mass, and therefore can be difficult to directly probe with current observations of cosmological structure. Alternative indirect probes of the cutoff scale are therefore necessary, and in this direction, I will present a study of the expected correlations between the cutoff mass and the results from two different types of WIMP searches: direct detection experiments and searches for neutrinos from WIMP annihilation in the sun. Finally, it has been postulated that late time kinetic decoupling could lead to resolution of some of the outstanding issues in the cold dark matter paradigm, such as the missing satellites problem. To conclude the talk, I will present results of ours and others investigating the viability of particle models that would lead to this late time decoupling.