Related papers: Axion Perturbations: A General Analytical Treatmen…
String scenarios generically predict that we live in a so called axiverse: the Universe with about a hundred of light axion species which are decoupled from the Standard Model particles. However, the axions can couple to the inflaton which…
We study the evolution of perturbations during the domination and decay of a massive particle species whose mass and decay rate are allowed to depend on the expectation value of a light scalar field. We specialize in the case where the…
A generic low-energy prediction of string theory is the existence of a large collection of axions, commonly known as a string axiverse. Axions also have a natural cosmological production mechanism, vacuum misalignment, making them…
Models in which dark energy interacts with dark matter have been proposed in the literature to help explain why dark energy should only come to dominate in recent times. In this paper, we present a dynamical framework to calculate…
A system of light axions comprising a classical axion field, one candidate for dark matter, has an instability that can rapidly mix in photon pairs in a coherent fashion if initiated by a quantum break (which eliminates the need for seeds.)…
The interaction between the dark/mirror sector and the ordinary sector is considered, where the two sectors interact with each other by sharing the same QCD axion field. This feature makes the mixing between ordinary and dark/mirror photons…
The early universe grants access to energy scales far beyond those achievable in terrestrial experiments and allows unstable Standard Model particles to play an active dynamical role. In this contribution, we focus on recent studies aimed…
Relativistic axions can be readily produced in a broad variety of transient sources, such as axion star bosenova explosions, supernovae or even evaporating primordial black holes. We develop a general framework describing the resulting…
Axion-CMB scenario is an interesting possibility to explain the temperature anisotropy of the cosmic microwave background (CMB) by primordial fluctuations of the QCD axion \cite{Iso:2020pzv}. In this scenario, fluctuations of radiations are…
We consider a nonminimally coupled scalar field as a potential cold dark matter candidate. These models are natural extensions of the ultralight axion models which are based on minimally coupled scalar fields. Such ultralight scalar fields…
Scenarios with axion-like particles of variable masses, from the milli-eV range to ultralight, can be generated in a natural way in the context of effective field theory models with anomalous $U(1)$ gauge symmetries. They include…
Axions have emerged as compelling candidates for describing the dark sector of the Universe. In this work, we explore quintessence models inspired by axion-like potentials as a dynamical alternative to the cosmological constant. These…
Motivated UV frameworks generically predict the existence of multiple axion fields. Their interplay gives rise to novel collective phenomena - including level crossings and the formation of string bundles - which modify the predicted mass…
We demonstrate that ultralight axion dark matter with a coupling to photons induces an oscillating global terrestrial magnetic field signal in the presence of the background geomagnetic field of the Earth. This signal is similar in…
We investigate the non-perturbatively generated axion-like particle (ALP) potential, involving fermions in the dark sector that couple to the ALP, in an early cosmological inflationary stage with the ALP being a spectator field. The…
We introduce a mechanism for multi-component dark matter (DM) that originates from axion mixing and present some of its defining properties. In this context, multi-component DM implies that the cold DM is composed of the QCD axion and many…
The axion is the most attractive candidate to solve the strong CP problem in QCD. If it exists, the inflationary universe produces axion fluctuations which are mixtures of isocurvature and adiabatic fluctuations in general. We investigate…
An ultra-light axion with CP violating interactions with a dark sector and CP preserving interactions with the visible sector can act as a novel portal between dark matter and the Standard Model. In such theories, dark matter sources an…
Consistent frameworks of quantum gravity often predict the existence of large numbers of ultralight pseudoscalar degrees of freedom, forming the phenomenological landscape of the String Axiverse. The complexity of the extra-dimensional…
We present an overview of recent developments in the detection of light bosonic dark matter, including axion, pseudoscalar axion-like and scalar dark matter, which form either a coherently oscillating classical field or topological defects…