Related papers: QCD Axion Dark Matter from a Late Time Phase Trans…
Recent observations of the space distribution of quasars indicate a very notable peak in space density at a redshift of $2$ to $3$.It is pointed out in this article that this may be the result of a phase transition which has a critical…
We study the mirror world with dark matter arising from the thermal freeze-out of the lightest, stable mirror particle -- the mirror electron. The dark matter abundance is achieved for mirror electrons of mass 225 GeV, fixing the mirror…
A new scheme for lightest supersymmetric particle (LSP) dark matter is introduced and studied in theories of TeV supersymmetry with a QCD axion, $a$, and a high reheat temperature after inflation, $T_R$. A large overproduction of axinos…
Axion dark matter inevitably generates electromagnetic radiation in quantum Hall effect experiments that use strong magnetic fields. Although these emissions are very weak, we have shown using a QCD axion model that they influence the…
We study the topological susceptibility in 2+1 flavor QCD above the chiral crossover transition temperature using Highly Improved Staggered Quark action and several lattice spacings, corresponding to temporal extent of the lattice,…
Hot axions, thermally produced in the Early Universe, would contribute to dark radiation and are thus subject to present and future constraints from $N_{\rm eff}$. In this paper we quantify the contribution to $N_{\rm eff}$ and its…
The QCD axion and axion-like particles, as leading dark matter candidates, can also have interesting implications for dark matter substructures if the Peccei-Quinn symmetry is broken after inflation. In such a scenario, axion perturbations…
If one simultaneously invokes the SUSY solution to the gauge hierarchy problem and the PQ solution to the strong CP problem, then one might expect mixed axion/neutralino dark matter (DM), i.e. two dark matter particles. In this case, dark…
We revisit the cosmology of the supersymmetric QCD axion, highlighting the existence of a serious cosmological axino problem that is fully analogous to the gravitino problem of overclosure via thermal production. A general analysis implies…
We observe that photon cooling after big bang nucleosynthesis (BBN) but before recombination can remove the conflict between the observed and theoretically predicted value of the primordial abundance of $^7$Li. Such cooling is ordinarily…
We analyze the stability of the vacuum and the electroweak phase transition in the NMSSM close to the Peccei-Quinn symmetry limit. This limit contains light Dark Matter (DM) particles with a mass significantly smaller than the weak scale…
We present a novel candidate for cold dark matter consisting of condensed Cooper pairs in a theory of interacting fermions with broken chiral symmetry. Establishing the thermal history from the early radiation era to the present, the…
We analyze a simple Split Supersymmetry scenario where fermion masses come from anomaly mediation, yielding m_s ~ 1000 TeV, m_{3/2} ~ 100 TeV, and m_f ~ 1 TeV. We consider non-thermal dark matter production in the presence of moduli, and we…
It is conventionally assumed that the physics underlying the Peccei-Quinn (PQ) mechanism for addressing the strong CP problem is at very high energies, orders of magnitude above the weak scale. However, this may not be the case in general…
We show that the upper bound of the classical QCD axion window can be significantly relaxed for low-scale inflation. If the Gibbons-Hawking temperature during inflation is lower than the QCD scale, the initial QCD axion misalignment angle…
Standard Model extensions with light axions are well-motivated by the observed Dark Matter abundance and the Peccei-Quinn solution to the Strong CP Problem. In general such axions can have large flavor-violating couplings to SM fermions,…
The axion is arguably one of the best motivated candidates for dark matter. For a decay constant greater than about 10^9 GeV, axions are dominantly produced non-thermally in the early universe and hence are "cold", their velocity dispersion…
We discuss current cosmological constraints on axions, as well as future sensitivities. Bounds on axion hot dark matter are discussed first, and subsequently we discuss both current and future sensitivity to models in which axions play the…
The axion field, the angular direction of the complex scalar field associated with the spontaneous symmetry breaking of the Peccei-Quinn (PQ) symmetry, could have originated with initial non-zero velocity. The presence of a non-zero angular…
A variety of supersymmetric models give rise to a split mass spectrum characterized by very heavy scalars but sub-TeV gauginos, usually with a wino-like LSP. Such models predict a thermally-produced underabundance of wino-like WIMP dark…