Studies of Dark Matter and Supersymmetry

Abstract

We perform four studies of beyond the Standard Model physics. First, we generally investigate operators that can explain dark matter's decay or annihilation to a keV photon line, and apply the analysis to the specific case of a 3.5 keV line in Andromeda and galaxy clusters. Next, we present a non-standard supersymmetry model, Stealth SUSY, which can evade bounds on superpartners from direct searches. This is because of suppressed missing energy due to the model's decay patterns which are different from those in the Minimal Supersymmetric Standard Model. We place limits on stops and gluinos using searches at the 8 TeV LHC. Third, the current experimental constraints of dark matter composed of neutralinos are summarized. Since an MeV mass splitting between neutral higgsinos is difficult to prove experimentally, we consider whether the heating of white dwarfs by captured higgsinos annihilating can test higgsino dark matter. We determine that observations of white dwarfs could be useful, if they are in regions of large dark matter density, such as dwarf galaxies. Finally, we perform a fit to current cosmological data from the CMB, BAO, LSS and Lyman-alpha forest for a model of dark matter which interacts with dark radiation. In this model, the dark matter transforms in the fundamental representation of dark SU(N) and is the neutral component of an SU(2)-weak triplet. From the fit to cosmological data, we find marginal evidence for the dark matter-dark radiation model, so we forecast constraints on the model parameters by performing a Fisher forecast analysis with the LSST galaxy survey and the CMB S4 survey.