Related papers: The $\pi$-axion and $\pi$-axiverse of dark QCD
Axion and axion-like particles (ALPs) are a prominent candidate for physics beyond the Standard Model, and can play an important role in cosmology, serving as dark matter or dark energy, or both, drawing motivation in part from the string…
If the QCD axion solves the strong CP problem then light axion-like-particles (ALPs) are expected to be ubiquitous in string theory - the string axiverse. Such ALPs can be the QCD axion and constitute dark matter (DM) or radiation,…
Axions are a leading dark matter candidate. In this work, we study the detectability of a multi-axion-like model, dubbed the $\pi$-axiverse, that is distinguishable from the string axiverse. The dark matter candidates are $N^2-1$…
The string/$M$ theory Axiverse -- a plethora of very light Axion Like Particles (ALPs) with a vast range of masses -- is arguably a generic prediction of string/$M$ theory. String/$M$ theory also tends to predict that the early Universe is…
Dark matter (DM) can be composed of a collection of axions, or axion-like particles (ALPs), whose existence is due to the spontaneous breaking of the Peccei-Quinn $U(1)$ symmetry which is the most compelling solution of the strong…
The QCD axion was originally predicted as a dynamical solution to the strong CP problem. Axion like particles (ALPs) are also a generic prediction of many high energy physics models including string theory. Theoretical models for axions are…
Cosmology and particle physics are closer today than ever before, with several searches underway at the interface between cosmology, particle physics, and field theory. The mystery of dark matter (DM) is one of the greatest common unsolved…
The quest to understand the nature of dark matter and dark energy motivates a deep exploration into axion physics, particularly within the framework of string theory. Axions, originally proposed to solve the strong CP problem, emerge as…
Dark matter (DM) refers to a new type of matter that may explain observed rotation curves of galaxies and the composite structure of the Universe. It may couple to the Standard Model particles via portals, which include the possibility of…
The string axiverse predicts a unique connection between the high scales approachable only through theory and the low energies within reach of experimental verification: a multitude of light, feebly interacting axions. In order to capture…
Standard Model extensions with light axions are well-motivated by the observed Dark Matter abundance and the Peccei-Quinn solution to the Strong CP Problem. In general such axions can have large flavor-violating couplings to SM fermions,…
The strong CP problem of QCD is at heart a problem of naturalness: why is the F\tilde{F} term highly suppressed in the QCD Lagrangian when it seems necessary to explain why there are three and not four light pions? The most elegant solution…
We review how axion-like particles (ALPs) naturally emerge in the low-energy effective field theory of string compactifications. We focus on the study of their mass spectrum and couplings, stressing that they depend on the mechanism used to…
Axion-like particles (ALPs) are a compelling candidate for dark matter (DM), whose production is associated with the formation of a string-wall network. If walls bounded by strings persist, which requires the potential to have multiple…
We propose heavy axions as a natural superheavy dark matter candidate in string theory, with the relic density of dark matter originating in quantum fluctuations during cosmic inflation. String Theory is well known for the possibility of…
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…
Axions and axion-like particles (ALPs) are some of the most popular candidates for dark matter, with several viable production scenarios that make different predictions. In the scenario in which the axion is born after inflation, its field…
We discuss the idea that the model-independent (MI) axion of string theory is the source of quintessential dark energy. The scenario is completed with a composite QCD axion from hidden sector squark condensation that could serve as dark…
The dark dimension scenario, which is motivated from Swampland principles and predicts a single micron scale extra dimension, suggests a consistent framework for the dark sector of the universe. We consider the implications of this scenario…
We discuss a QCD-scale composite axion model arising from dark QCD coupled to QCD. The presently proposed scenario not only solves the strong CP problem, but also is compatible with the preheating setup for the QCD baryogenesis. The…