Related papers: Altered Axion Abundance from a Dynamical Peccei-Qu…
Global-symmetry violating higher-dimension operators, expected to be induced by Planck-scale physics, in general drastically alter the properties of the axion field associated with the Peccei-Quinn solution to the strong-CP problem, and…
The post-inflationary Peccei-Quinn (PQ) symmetry breaking scenario provides a unique opportunity to pinpoint the QCD axion dark matter mass, which is a crucial input for laboratory experiments that are designed for probing specific mass…
We propose a new regime of minimal QCD axion dark matter that lies between the pre- and post-inflationary scenarios, such that the Peccei-Quinn (PQ) symmetry is restored only on sufficiently large spatial scales. This leads to a novel…
We propose a framework in which the QCD axion has an exponentially large coupling to photons, relying on the "clockwork" mechanism. We discuss the impact of present and future axion experiments on the parameter space of the model. In…
We study the cosmological evolution of a light QCD axion and identify the parameter space to obtain the correct relic dark matter abundance. The axion potential is flattened at the origin, corresponding to the only minimum, while it is…
Physics beyond the Standard Model predicts the possible existence of new particles that can be searched at the low energy frontier in the sub-eV range. The OSQAR photon regeneration experiment looks for "Light Shining through a Wall" from…
We show that the hybrid inflation is naturally realized in the framework of a supersymmetric axion model, which is consistent with the WMAP observation if the Peccei-Quinn symmetry breaking scale is around 10^{15}GeV. By solving the post…
Axions and axion-like particles generically appear in extensions of the Standard Model. While many searches assume only a single axion species, there may exist a whole spectrum of multiple such fields. We develop general formulas for…
A light singlet scalar field feebly coupled through the super-renormalizable Higgs portal provides a minimal and well-motivated realization of ultra-light bosonic dark matter. We study the cosmological production of dark matter in this…
We discuss some cosmological aspects of supersymmetric axion models in which the axion scale is radiatively generated in terms of the weak scale and the Planck scale. They include thermal inflation, axions produced by the decay of…
Cosmological scalar fields coupled to the Standard Model drive temporal variations in the fundamental constants that grow with redshift, positioning the early Universe as a powerful tool to study such models. We investigate the dynamics and…
Results of a recent study on how the Quintessence scalar could affect the relic abundance of dark matter particles are presented.
Motivated by their potential role as dark matter, we study the cosmological evolution of light scalar and vector fields non-minimally coupled to gravity. Our focus is on a situation where the dominant contribution to the energy density…
In the QCD axion dark matter scenario with post-inflationary Peccei-Quinn symmetry breaking, the number density of axions, and hence the dark matter density, depends on the length of string per unit volume at cosmic time $t$, by convention…
We investigate what it takes for the axion to address the strong CP problem in the presence of explicit Peccei-Quinn (PQ) symmetry breaking effects besides the strong interaction. In cases where the PQ-Higgsing scalar field directly couples…
In the chaotic inflation models, quantum fluctuations for axion fields lead to the overproduction of domain walls and too large isocurvature fluctuations which is inconsistent with the observations of cosmic microwave background…
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 propose a relaxation mechanism for the initial misalignment angle of the pre-inflationary QCD axion with a large decay constant. The proposal addresses the challenges posed to the axion dark matter scenario by an overabundance of axions…
We derive the necessary conditions to build a class of invisible axion models with Flavor Changing Neutral Currents at tree-level controlled by the fermion mixing matrices and present an explicit model implementation. A horizontal…
The axion is a light pseudoscalar particle postulated to solve issues with the Standard Model, including the strong CP problem and the origin of dark matter. In recent years, there has been remarkable progress in the physics of axions in…