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Progress in observational cosmology over the past five years has established that the Universe is dominated dynamically by dark matter and dark energy. Both these new and apparently independent forms of matter-energy have properties that…
We obtain the first cosmological constraints on interactions between dark matter and protons within the formalism of nonrelativistic effective field theory developed for direct detection. For each interaction operator in the effective…
Dark matter might be in the form of a dark plasma in the Milky Way halo. Specifically, we consider here a hidden sector consisting of a light `dark electron' and a much heavier `dark proton', each charged under an unbroken $U(1)'$ gauge…
One of the most stimulating recent ideas in particle physics involves a possibility that our universe has additional compactified spatial dimensions, perhaps as large as 1 mm. In this review, we discuss the results of recent experimental…
Dark matter is a fundamental constituent of the universe, which is needed to explain a wide variety of astrophysical and cosmological observations. Although the existence of dark matter was first postulated nearly a century ago and its…
Measurements of the primordial element abundances provide us with an important probe of our universe's early thermal history, allowing us to constrain the expansion rate and composition of our universe as early as $\sim 1 \, {\rm s}$ after…
The EDGES Collaboration has recently reported the detection of a stronger-than-expected absorption feature in the global 21-cm spectrum, centered at a frequency corresponding to a redshift of z ~ 17. This observation has been interpreted as…
Motivated by string-theoretic swampland conjectures, the existence of a dark fifth dimension, whose size is roughly 1 -- 10 microns, has been proposed. A great deal of supporting evidence has been presented, and definitive experimental…
The existence of dark matter is currently one of the strongest motivations for physics beyond the standard model. Its implications for future colliders are discussed. In the case of neutralino dark matter, cosmological bounds do not provide…
We present new observational constraints on the elastic scattering of dark matter with electrons for dark matter masses between 10 keV and 1 TeV. We consider scenarios in which the momentum-transfer cross section has a power-law dependence…
Dark matter in the universe seems to be one of the most important puzzles science has to face in this moment. In this essay we point out that dark matter could be a spin-0 fundamental interaction of Nature rather than a simple particle.…
One of the drawbacks of conventional grand unification scenarios has been that the unification scale is too high to permit direct exploration. In this paper, we show that the unification scale can be significantly lowered (perhaps even to…
Some direct detection experiments have recently collected excess events that could be interpreted as a dark matter (DM) signal, pointing to particles in the $\sim$10 GeV mass range. We show that scenarios in which DM can self-annihilate…
The existence of predominantly cold non-baryonic dark matter is unambiguously demonstrated by several observations (e.g., structure formation, big bang nucleosynthesis, gravitational lensing, and rotational curves of spiral galaxies). A…
Theories of dark matter that support bound states are an intriguing possibility for the identity of the missing mass of the Universe. This article proposes a class of models of supersymmetric composite dark matter where the interactions…
We examine the late-time (nucleosynthesis and later) cosmological implications of brane-world scenarios having large (millimeter sized) extra dimensions. In particular, recent proposals for understanding why the extra dimensions are so…
The requirement that their gravitational binding self-energy density must at least equal the background repulsive dark energy density for large scale cosmic structures implies a mass-radius relation of M/R^2 ~ 1g/cm^2, as pointed out…
We assume dark matter to be a cosmological self-gravitating Bose-Einstein condensate of non-relativistic ultralight scalar particles with competing gravitational and repulsive contact interactions and investigate the observational…
This article reviews recent progress in observational determination of the properties of dark matter on small astrophysical scales, and progress towards the European Extremely Large Telescope. Current results suggest some surprises: the…
The lack of evidence for low energy supersymmetry at the LHC implies a supersymmetry scale in excess a TeV. While this is consistent (and even helpful) with a Higgs boson mass at $\approx$ 125 GeV, simple supersymmetric models with scalar…