Related papers: Axiology
In supersymmetric axion models, if the gravitino or axino is the lightest SUSY particle (LSP), the other is often the next-to-LSP (NLSP). We investigate the cosmology of such a scenario and point out that the lifetime of the NLSP naturally…
We propose a simple extension of the minimal supersymmetric standard model by introducing a gauge singlet in addition to right-handed neutrinos. The model resolves the strong CP problem by Pecci-Quinn symmetry, explains the origin of…
Many models of dark matter QCD axion requires inflation at a scale $H_{\text{inf}} \lesssim 10^{6}$~GeV and hence does not allow for a detectable tensor mode fluctuation. This is because the domain wall problem forces the Peccei--Quinn…
We consider the axion arising from five-dimensional supergravity in the presence of boundaries. We find the approximate bosonic effective action to estimate the lower bound on the "Peccei-Quinn" energy scale with a flat bulk. With a warped…
Axions solve the Strong CP Problem and are a cold dark matter candidate. The combined constraints from accelerator searches, stellar evolution limits and cosmology suggest that the axion mass is in the range $3 \cdot 10^{-3} > m_a >…
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…
Axions are candidates for dark matter in the universe.We develop an accurate Boltzmann code to calculate the linear growth of the plasma. As an interesting example, we investigate a mixed dark matter model consisting of cold dark matter…
Axions provide a solution to the strong CP problem and are excellent dark matter candidates. The presence of additional sources of CP violation, for example to account for the matter/antimatter asymmetry of the universe, can lead to…
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…
Axino arises in supersymmetric versions of axion models and is a natural candidate for cold or warm dark matter. Here we revisit axino dark matter produced thermally and non-thermally in light of recent developments. First we discuss the…
Incorporating the QCD axion and simultaneously satisfying current constraints on the dark matter density and isocurvature fluctuations requires non-minimal fine-tuning of inflationary parameters or the axion misalignment angle (or both) for…
We derive general constraints on supersymmetric extension of axion models, in particular paying careful attention to the cosmological effects of saxion. It is found that for every mass range of the saxion from keV to TeV, severe constraints…
Slightly extending a right-handed neutrino version of the $3-3-1$ model, we show that it is not only possible to solve the strong CP problem but also to give the total dark matter abundance reported by the Planck collaboration.…
Axions with variable masses, in the context of a scalar--tensor gravity theory, give a large entropy production during the matter era. The subsequent axion dilution is proportional to their present energy density. Depending on the…
Relativistic axions are good candidates for the dark radiation for which there are mounting observational hints. The primordial decays of heavy fields produce axions which are ultra-energetic compared to thermalised matter and inelastic…
The axino is a promising candidate for dark matter in the Universe. It is electrically and color neutral, very weakly interacting, and could be - as assumed in this study - the lightest supersymmetric particle, which is stable for unbroken…
The axino, the fermionic superpartner of the axion, is a well-motivated candidate for cold dark matter if it is the lightest supersymmetric particle. Since the axino couples very weakly to the matter multiplets, the next-to-lightest…
The Peccei-Quinn solution to the strong CP problem provides a motivated framework rich in cosmological consequence. Thermal axion production is unavoidable if there is a thermal bath at early times. Scattering and decay processes of bath…
Ultra-light axions ($m_a\lesssim 10^{-18}$eV), motivated by string theory, can be a powerful probe of the energy scale of inflation. In contrast to heavier axions the isocurvature modes in the ultra-light axions can coexist with observable…
We demonstrate that the observed cosmological excess of matter over antimatter may originate from a heavy QCD axion that solves the strong CP problem but has a mass much larger than that given by the Standard Model QCD strong dynamics. We…