Related papers: Axion Free-kick Misalignment Mechanism
Axions and axion-like particles are compelling candidates for the missing dark matter of the universe. As they undergo gravitational collapse, they can form compact objects such as axion stars or even black holes. In this paper, we study…
We explore the phenomenology of QCD axion and axion-like particle (ALP) dark matter production via misalignment during inflationary reheating. We investigate scenarios involving inflaton oscillating in a generic potential $\sim \phi^n$,…
In addition to spectacular signatures such as black hole superradiance and the rotation of CMB polarization, the plenitude of axions appearing in the string axiverse may have potentially dangerous implications. An example is the…
We study an axion-like particle (ALP) that experiences the first-order phase transition with respect to its mass or potential minimum. This can be realized if the ALP obtains a potential from non-perturbative effects of SU($N$) gauge theory…
In this work we introduce an effective model of $f(R)$ gravity containing a non-minimal coupling to the axion scalar field. The axion field is described by the misalignment model, in which the primordial $U(1)$ Peccei-Quinn symmetry is…
Axions and axion-like particles are ubiquitous in extensions of the Standard Model and offer a unifying framework for addressing open problems in cosmology. Depending on their mass and interactions, axions can act as dark matter, drive…
Axion-like-particles are a well-motivated extension of the Standard Model that can mediate interactions between the dark matter and ordinary matter. Here we consider an axion portal between the two sectors, where the axion couples to dark…
We provide a compact review on recent developments on axion $F(R)$ gravity. The axion field is a string theory originating theoretical particle that is a perfect candidate for low-mass particle dark matter. In this review we present how a…
Why matter and dark matter contents of the universe are of the same order of magnitude, is one of the puzzles of modern cosmology. At the face of it, this would seem to point towards a basic similarity between matter and dark matter,…
We consider Dark Matter composed of an oscillating singlet scalar field. On top of the mass term, the scalar is equipped with a potential spontaneously breaking Z_2-symmetry. This potential dominates at early times and leads to the…
Axions can naturally be very light due to the protection of an (approximate) shift symmetry. Because of their pseudoscalar nature, the long-range force mediated by the axion at tree level is spin dependent, which cannot lead to observable…
We propose a novel method to detect axion dark matter based on a topological phenomenon known as the shift current. We exploit the second-order nonlinearity of the shift current by applying a strong oscillating electric field. This field…
Axion rotations can simultaneously explain the dark matter abundance and the baryon asymmetry of the Universe by kinetic misalignment and axiogenesis. We consider a scenario in which the Peccei-Quinn symmetry breaking field is as large as…
A system of light axions comprising a classical axion field, one candidate for dark matter, has an instability that would rapidly mix in photon pairs in a coherent fashion if the system were initially seeded by some tiny amount of such…
The recently reported X-ray line signal at $E_\gamma \simeq 3.5\, {\rm keV}$ from a stacked spectrum of various galaxy clusters and the Andromeda galaxy may be originating from a decaying dark matter particle of the mass $2 E_\gamma$. A…
One of the major challenges of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the…
We study the cosmology of the dark sector consisting of (ultra) light scalars. Since the scalar mass is radiatively unstable, a special explanation is required to make the mass much smaller than the UV scale. There are two well-known…
We propose a new non-thermal mechanism of dark matter production based on vacuum misalignment. A global $X$-charge asymmetry is generated at high temperatures, under which both the will-be Higgs and the dark matter are charged. At lower…
Existing searches for cosmic axions relics have relied heavily on the axion being non-relativistic and making up dark matter. However, light axions can be copiously produced in the early Universe and remain relativistic today, thereby…
In the early universe, the potential of a scalar field can be significantly modified, and the scalar field may be trapped for a long time in a different location than the current vacuum. The trapping effect can increase or decrease the…