We review the landscape of QCD axion models. Theoretical constructions that extend the
window for the axion mass and couplings beyond conventional regions are highlighted and …

Axions and other very light axion-like particles appear in many extensions of the Standard
Model, and are leading candidates to compose part or all of the missing matter of the …

Although dark matter is a central element of modern cosmology, the history of how it became
accepted as part of the dominant paradigm is often ignored or condensed into an anecdotal …

Four decades after its prediction, the axion remains the most compelling solution to the
strong-CP problem and a well-motivated dark matter candidate, inspiring a host of elegant …

Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden
photons (HPs), may be non-thermally produced via the misalignment mechanism in the …

Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the
known strong, weak, or electromagnetic forces, are a particularly compelling possibility for …

We revise the bound from the supernova SN1987A on the coupling of ultralight axion-like
particles (ALPs) to photons. In a core-collapse supernova, ALPs would be emitted via the …

A bstract We study closed string axions in type IIB orientifold compactifications. We show that
for natural values of the background fluxes the moduli stabilisation mechanism of the …

Scattering and decay processes of thermal bath particles involving heavy leptons can dump
hot axions in the primordial plasma around the QCD phase transition. We compute their relic …

There are a number of observational hints from astrophysics which point to the existence of
stellar energy losses beyond the ones accounted for by neutrino emission. These excessive …