Relic densities of dark matter in the U(1)-extended NMSSM and the gauged axion supermultiplet (original) (raw)

Dark matter axions revisited

Physical Review D, 2009

We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae, and assume an inflationary scenario and standard cosmology. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass ma=67±2μeV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for ma<15meV provided a specific value of the initial misalignment angle θi is chosen in correspondence to a given value of its mass ma. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle θi.

Cosmological properties of a gauged axion

Physical Review D, 2010

We analyze the most salient cosmological features of axions in extensions of the Standard Model with a gauged anomalous extra U (1) symmetry. The model is built by imposing the constraint of gauge invariance in the anomalous effective action, which is extended with Wess-Zumino counterterms. These generate axion-like interactions of the axions to the gauge fields and a gauged shift symmetry. The scalar sector is assumed to acquire a non-perturbative potential after inflation, at the electroweak phase transition, which induces a mixing of the Stückelberg field of the model with the scalars of the electroweak sector, and at the QCD phase transition. We discuss the possible mechanisms of sequential misalignments which could affect the axions of these models, and generated, in this case, at both transitions. We compute the contribution of these particles to dark matter, quantifying their relic densities as a function of the Stückelberg mass. We also show that models with a single anomalous U(1) in general do not account for the dark energy, due to the presence of mixed U (1) − SU (3) anomalies.

Axions as a model of Dark Matter

Journal of Student Research

The true nature of dark matter is an extremely important and fundamental problem in the study of astrophysics, particle physics, cosmology and many other areas within the study of physics. This paper presents experimental evidence for the existence of dark matter through discussing the experimental results of mass profiling a galaxy and gravitational lensing. The fundamental properties of dark matter are then discussed, and evidence for these properties is presented. This allows further discussion of one of the most promising models of dark matter - the axion. The purpose of this paper is to present the evidence for the axion model, describe the nature of the theoretical axion particle, and to highlight the effects this model would have on other theories in physics such as solving the Strong CP Problem in the theory of quantum chromodynamics.

Axions in the Universe

Observational Cosmology, 1987

The observational evidence for the presence of dark matter is now generally accepted, with no lack of possible candidates (see e.g. Dekel, Einasto, and Rees 1986). The proposed candidates are devided into two groups, baryonic and non-baryonic. The latter is further devided to hot and cold dark matter. For the cold dark matter, among the first to be proposed is the axion. In this paper we shall not dwell on numerous cold dark matter candidates offered by particle physicists, for there are review articles on the subject (see e.g. Turner 1986, Primack 1986). The main purpose of the present report is to suggest that neutron star cooling theory and future space satellite programs (e.g. AXAF, XAO, LXAO) have a potential for offering the best astrophysical constraint on the axion mass and hence, giving valuable insight to some cosmological problems. Even though other candidates for cold dark matter are perfectly plausible, axions may have the following advantages. Their presence was predicted, independently of cosmology, as a natural solution to the strong CP problem (Peccei and Quinn 1977). Also, once we accept their presence, we can carry out specific calculations, to predict various properties (e.g. their emissivities).

Supersymmetric axion grand unified theories and their predictions

Physical Review D

We introduce a class of unified supersymmetric axion theories with unified and PQ symmetries broken by the same set of fields at a scale ∼ 2 × 10 16 GeV. A typical domain wall number of order 30 leads to an axion decay constant f a of order 10 15 GeV. Inflation generates a large saxion condensate giving a reheat temperature T R below the QCD scale for supersymmetry breaking of order 1-10 TeV. Axion field oscillations commence in the saxion matter-dominated era near the QCD scale, and recent lattice computations of the temperature dependence of the axion mass in this era allow a controlled calculation of the axion dark matter abundance. A successful prediction of this abundance results for an initial axion misalignment angle of order unity, θ i ∼ 1. A highly correlated set of predictions are discussed for f a , T R , the supersymmetric Higgs mass parameter µ, the amount of dark radiation ∆N ef f , the proton decay rate Γ(p → e + π 0), isocurvature density perturbations and the B-mode of the cosmic microwave background. The last two are particularly interesting when the energy scale of inflation is also of order 10 16 GeV. * and f = Σ(+1) 2 Σ(−2)/M 3 * where S and Σ are SU (5) singlets and adjoints, respectively, and the PQ charges are shown in parenthesis. An example with f ∼ (Σ + Σ −) and no driver field is

Axion cold dark matter revisited

Journal of Physics: Conference Series, 2010

We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae [1], and assume an inflationary scenario and standard cosmology. We also upgrade the treatment of anharmonicities in the axion potential, which we find important in certain cases. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass ma = (85 ± 3) µeV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for ma < 15 meV provided a specific value of the initial misalignment angle θi is chosen in correspondence to a given value of its mass ma. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle θi.

Relic Densities of Gauged Axions and Supersymmetry

Nuclear Physics B - Proceedings Supplements, 2011

We illustrate the structure and the main phenomenological features of a supersymmetric model (the USSM-A) built following a bottom-up approach and containing an anomalous abelian gauge symmetry. This model supports a gauged axion in its spectrum and provides a generalization of the global (supersymmetric) Peccei-Quinn construction. Complete simulations of the neutralino relic density are performed. Bounds from CAST and WMAP, combined with dark matter simulations, provide significant constraints on the scale of the interactions between the axion and the gauge fields.

Mixed axion/neutralino cold dark matter in supersymmetric models

Journal of Cosmology and Astroparticle Physics, 2011

We consider supersymmetric (SUSY) models wherein the strong CP problem is solved by the Peccei-Quinn (PQ) mechanism with a concommitant axion/axino supermultiplet. We examine R-parity conserving models where the neutralino is the lightest SUSY particle, so that a mixture of neutralinos and axions serve as cold dark matter (a Z 1 CDM). The mixed a Z 1 CDM scenario can match the measured dark matter abundance for SUSY models which typically give too low a value of the usual thermal neutralino abundance, such as models with wino-like or higgsino-like dark matter. The usual thermal neutralino abundance can be greatly enhanced by the decay of thermally-produced axinos (ã) to neutralinos, followed by neutralino re-annihilation at temperatures much lower than freeze-out. In this case, the relic density is usually neutralino dominated, and goes as ∼ (f a /N)/m 3/2 a. If axino decay occurs before neutralino freeze-out, then instead the neutralino abundance can be augmented by relic axions to match the measured abundance. Entropy production from late-time axino decays can diminish the axion abundance, but ultimately not the neutralino abundance. In a Z 1 CDM models, it may be possible to detect both a WIMP and an axion as dark matter relics. We also discuss possible modifications of our results due to production and decay of saxions. In the appendices, we present expressions for the Hubble expansion rate and the axion and neutralino relic densities in radiation, matter and decaying-particle dominated universes.