Related papers: Opening the 1$\,$Hz axion window
Current upper bounds of the neutron electric dipole moment constrain the physically observable quantum chromodynamic (QCD) vacuum angle $|\bar\theta| \lesssim 10^{-11}$. Since QCD explains vast experimental data from the 100 MeV scale to…
A major fraction of the mass content of the universe is composed of dark matter (DM), i.e. particles not interacting significantly with electromagnetic radiation, with ordinary matter or self-interacting (cold dark matter). The axion is…
If axion-like particles (ALPs) constitute a major part of dark matter (DM), due to the bosonic nature and a relative small mass, they could behave differently from the point like dark matter particles on the formation of the cosmic…
We assume that dark matter is comprised of axion-like particles (ALPs) generated by the realignment mechanism in the post-inflationary scenario. This leads to isocurvature fluctuations with an amplitude of order one for scales comparable to…
Axions and axion-like particles (ALPs) are one of the most widely discussed extensions of the Standard Model when it comes to the strong CP problem and dark matter candidates. Current experiments are focused on the indirect searches of…
We consider the largest observed sample including all intermediate-frequency peaked (IBL) and high-frequency peaked (HBL) flaring blazars above 100 GeV up to redshift $z = 0.6$. We show that the best-fit regression line of the emitted…
Axions are hypothesized particles believed to potentially resolve two major puzzles in modern physics: the strong CP problem and the nature of dark matter. Cavity-based axion haloscopes represent the most sensitive tools for probing their…
We introduce four supersymmetric (SUSY) axion models in which the strong CP problem and the $\mu$ problem are solved with the help of the Peccei-Quinn mechanism and the Kim-Nilles mechanism, respectively. The axion physics enriches the SUSY…
The axion is a light pseudoscalar particle which suppresses CP-violating effects in strong interactions and also happens to be an excellent dark matter candidate. Axions constituting the dark matter halo of our galaxy may be detected by…
The nature of dark matter is one of the longest-standing puzzles in science. Axions or axion-like particles are a key possibility, and arise in mechanisms to solve the strong CP problem but also in low-energy limits of string theory.…
Several extensions of the Standard Model predict the existence of Axion-Like Particles (ALPs), very light spin-zero bosons with a two-photon coupling. ALPs can give rise to observable effects in very-high-energy astrophysics. Above roughly…
The Strong CP Problem can be resolved by introducing an additional global symmetry known as Peccei-Quinn symmetry. Once PQ symmetry is broken the associated particle, the QCD axion, is a plausible dark matter candidate. Calculating the…
We assume axion-like particles (ALPs) to provide the full dark matter abundance and derive various lower bounds on the ALP mass. We contrast the post- and pre-inflationary symmetry breaking cases and present allowed regions in the plane of…
Axions and axion-like particles (ALPs) arise naturally in many extensions of the Standard Model and are among the well-motivated candidates for dark matter. In the presence of magnetic fields of galaxy clusters, Cosmic Microwave Background…
Axion-like particles (ALPs) can oscillate to photons and vice versa in electromagnetic fields. The photon-ALP oscillation provides an attractive solution to the apparent transparency of the Universe to TeV photons. The allowed parameter…
The QCD axion provides an elegant solution to the Strong CP Problem. While the minimal realization is vulnerable to the so-called "Axion Quality Problem", we will consider a more robust realization in the presence of a mirror sector related…
Current techniques cannot detect axion dark matter over much of its parameter space, particularly in the theoretically well-motivated region where the axion decay constant f_a lies near the GUT and Planck scales. We suggest a novel…
We review the physics potential of a next generation search for solar axions: the International Axion Observatory (IAXO). Endowed with a sensitivity to discover axion-like particles (ALPs) with a coupling to photons as small as…
Axion-like particles (ALPs) are well-motivated examples of light, weakly coupled particles in theories beyond the Standard Model. In this work, we study long-lived ALPs coupled exclusively to leptons in the mass range between $2 m_e$ and…
We explore whether the axion which solves the strong CP problem can naturally be much lighter than the canonical QCD axion. The $Z_\mathcal{N}$ symmetry proposed by Hook, with $\mathcal{N}$ mirror and degenerate worlds coexisting in Nature…