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 comprise a broad class of particles that can play a major role in explaining the
unknown aspects of cosmology. They are also well-motivated within high energy physics …

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 …

Axion emission by hot and dense plasmas is a new energy-loss channel for stars.
Observable consequences include a modification of the solar sound-speed profile, an …

A bstract Light pseudoscalars interacting pre-dominantly with Standard Model gauge
bosons (so-called axion-like particles or ALPs) occur frequently in extensions of the …

Abstract Axion-like particles (ALPs), relatively light (pseudo-) scalars coupled to two gauge
bosons, are a common feature of many extensions of the Standard Model. Up to now there …

We present an up-to-date review of Big Bang Nucleosynthesis (BBN). We discuss the main
improvements which have been achieved in the past two decades on the overall theoretical …

Axion-like particles with masses in the keV-GeV range have a profound impact on the
cosmological evolution of our Universe, in particular on the abundance of light elements …

We review the cosmological implications of a relic population of pseudo Nambu-Goldstone
bosons (pNGB) with an anomalous coupling to two photons, often called axion-like particles …

▪ Abstract Low-mass particles, such as neutrinos, axions, other Nambu-Goldstone bosons,
and gravitons, are produced in the hot and dense interior of stars. Therefore, astrophysical …