Hooman Davoudiasl

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We present a novel mechanism for generating both the baryon and dark matter densities of the Universe. A new Dirac fermion X carrying a conserved baryon number charge couples to the standard model quarks as well as a GeV-scale hidden sector. CP-violating decays of X, produced nonthermally in low-temperature reheating, sequester antibaryon number in the(More)
A light vector boson, Zd, associated with a ‘‘dark sector’’ Uð1Þd gauge group has been introduced to explain certain astrophysical observations as well as low energy laboratory anomalies. In such models, the Higgs boson may decay into X þ Zd, where X 1⁄4 Z, Zd or . Here, we provide estimates of those decay rates as functions of the Zd coupling through(More)
Warped 5-dimensional models, based on the original Randall-Sundrum geometry, have been extended beyond their initial purpose of resolving the gauge hierarchy problem. Over the past decade, various ingredients have been added to their basic structure in order to provide natural and predictive models of flavor and also to address existing constraints from(More)
We show that solar axion conversion to photons in the Earth's magnetosphere can produce an x-ray flux, with average energy omega approximately 4 keV, which is measurable on the dark side of the Earth. The smallness of the Earth's magnetic field is compensated by a large magnetized volume. For axion masses m(a) less, similar10(-4) eV, a low-Earth-orbit x-ray(More)
We show that weak scale vectorlike fermions with order one couplings to the Higgs can lead to a novel mechanism for a strongly first-order electroweak phase transition through their tendency to drive the Higgs quartic coupling negative. These same fermions could also enhance the loop-induced branching fraction of the Higgs into two photons, as suggested by(More)
We consider the phenomenological consequences of sampling multiple vacua during inflation motivated by an enormous landscape. A generic consequence of this sampling is the formation of domain walls, characterized by the scale mu of the barriers that partition the accessed vacua. We find that the success of big bang nucleosynthesis (BBN) implies mu > or = 10(More)
The muon anomalous magnetic moment exhibits a 3.6σ discrepancy between experiment and theory. One explanation requires the existence of a light vector boson, Z(d) (the dark Z), with mass 10-500 MeV that couples weakly to the electromagnetic current through kinetic mixing. Support for such a solution also comes from astrophysics conjectures regarding the(More)
It has recently been suggested that a scale-invariant "unparticle" sector with a nontrivial infrared fixed point may couple to the standard model (SM) via higher-dimensional operators. The weakness of such interactions hides the unparticle phenomena at low energies. We demonstrate how cosmology and astrophysics can place significant bounds on the strength(More)
A very light boson of mass O(10^{-22})  eV may potentially be a viable dark matter (DM) candidate, which can avoid phenomenological problems associated with cold DM. Such "fuzzy DM (FDM)" may naturally be an axion with a decay constant f_{a}∼10^{16}-10^{18}  GeV and a mass m_{a}∼μ^{2}/f_{a} with μ∼10^{2}  eV. Here, we propose a concrete model, where μ(More)