We propose a grand unified SU(5)$\times$U(1)$_X$ model, where the standard SU(5) grand unified theory is supplemented by minimal seesaw and a right-handed neutrino dark matter with an introduction of a global $Z_2$-symmetry. In the presence of three right-handed neutrinos (RHNs), the model is free from all gauge and mixed-gravitational anomalies. The SU(5) symmetry is broken into the Standard...
If dark matter annihilation is velocity dependent, then the J-factors associated with any astrophysical target depend on the full dark matter phase space distribution. We calculate these velocity-dependent J-factors for a variety of targets and a variety of choices for the velocity-dependence of DM annihilation. Significantly, we find that the choice of velocity-dependence affects the...
A leading dark matter candidate is a Weakly Interacting Massive Particle (WIMP). The observed dark matter abundance can be naturally obtained through freezeout of the thermal annihilation rate. The defining feature of a thermal WIMP is that its total annihilation cross section is specified through the thermally averaged cross section $\langle\sigma v\rangle$. Searches for dark matter...
We study a simple model of thermal dark matter annihilating to standard model neutrinos via the neutrino portal. A (pseudo-)Dirac sterile neutrino serves as a mediator between the visible and the dark sectors, while an approximate lepton number symmetry allows for a large neutrino Yukawa coupling and, in turn, efficient dark matter annihilation. The dark sector consists of two particles, a...
We explain the two upgoing ultra-high energy shower events observed by ANITA as arising from the decay in the Earth’s interior of the quasi-stable dark matter candidate in the CPT symmetric universe. The dark matter particle is a 480 PeV right-handed neutrino that decays into a Higgs boson and a light Majorana neutrino. The latter interacts in the Earth’s crust to produce a τ lepton that in...
Near a critical value of the wino mass where there is a zero-energy S-wave resonance at the neutral-wino-pair threshold, low-energy winos can be described by a zero-range effective field theory (ZREFT) in which the winos interact nonperturbatively through a contact interaction and through Coulomb interactions. The effects of wino-pair annihilation into electroweak gauge bosons are taken into...
Observational evidence for dark matter stems from its gravitational interactions, and as of yet there has been no evidence for dark matter interacting via other means. We examine models where dark matter interactions are purely gravitational in a Randall-Sundrum background. In particular, the Kaluza-Klein tower of gravitons which result from the warped fifth dimension can provide viable...
Scalar, fermionic, and vector WIMP-like dark matter may couple to the Standard Model through a massive spin-2 mediator. Mediators of this sort appear in extra-dimensional models, such as Randall-Sundrum models. We apply several parameter space constraints to phenomenological spin-2 mediated scenarios, including those arising from direct detection, indirect detection, relic density, collider...
