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Beyond the Standard Model: Dark Matter and Collider Physics

Colburn, Russell J, III

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Physics.
In this work we analyze dark matter annihilation in dwarf galaxies as well as scenarios of new physics relevant to current and future runs at the LHC. Our work with dark matter focuses on the implications for dark matter models from observations from the Fermi-LAT telescope while our work on LHC physics offers an explanation for the 750 GeV diphoton excess as well as a new possible decay channels of a scalar color octet. Using gamma-ray observations of dwarf spheroidal galaxies from the pass-7 Fermi-LAT experiment, we discuss the implications on dark matter models where dark matter annihilates to multiple final state configurations: where dark matter annihilates to third generation fermions and Standard Model vector bosons. We present limits in various slices of model parameter space both as limits on dark matter mass and in the context of effective operators. We visualize our bounds for models with multiple final state annihilations by projecting parameter space constraints onto triangles, a technique familiar from collider physics; and we compare our bounds to collider limits on equivalent models. We extend this analysis to the pass-8 Fermi-LAT observations of dwarfs by using a more robust “stacked” analysis using a joint-likelihood analysis to combine multiple dwarf galaxies. We once again look at dark matter annihilations to multiple final-state fermions and interpret these results in the context of the most popular simplified models, including those with s- and t-channel dark matter annihilation through scalar and vector mediators. Additionally, we compare our simplified model results to those of effective field theory contact interactions in the high-mass limit. We propose that the sbino, the scalar partner of a Dirac bino can explain the 750 GeV diphoton excess observed by the ATLAS and CMS collaborations. We analyze the minimal completion of the effective operator model in which the sbino couples to pairs of gauge bosons through loops of heavy sfermions, with the sfermion-bino coupling originating from scalar potential D-terms. We find that the sbino model may be fit the 750 GeV excess by considering gluon fusion processes with decay to diphotons. Finally, we explore the phenomenology of scalar fields in the adjoint representation of SM gauge groups at the LHC. We write a general set of dimension 5 effective operators in which SM adjoint scalars couple to pairs of standard model bosons. Using these effective operators, we explore new possible decay channels of a scalar color octet into a gluon and a Z boson, another gluon, or a photon. We recast several analyses from Run I of the LHC to find constraints on an a scalar octet decaying into these channels, and we project the discovery potential of color octets in our gluon+photon channel for the 14 TeV run of LHC.
Linda Carpenter (Advisor)
Stuart Raby (Committee Member)
Chris Hill (Committee Member)
Annika Peter (Committee Member)
137 p.

Recommended Citations

Citations

  • Colburn, III, R. J. (2017). Beyond the Standard Model: Dark Matter and Collider Physics [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1507215920939059

    APA Style (7th edition)

  • Colburn, III, Russell. Beyond the Standard Model: Dark Matter and Collider Physics. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1507215920939059.

    MLA Style (8th edition)

  • Colburn, III, Russell. "Beyond the Standard Model: Dark Matter and Collider Physics." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1507215920939059

    Chicago Manual of Style (17th edition)