Axions are hypothetical particles that may explain the observed dark matter density and the
non-observation of a neutron electric dipole moment. An increasing number of axion …

We derive model-independent quantization conditions on the axion couplings (sometimes
known as the anomaly coefficients) to the standard model gauge group [SU (3)× SU (2)× U …

Searches for dark matter decaying into photons constrain its lifetime to be many orders of
magnitude larger than the age of the Universe. A corollary statement is that the abundance …

Abstract If the Peccei-Quinn symmetry associated to an axion has ever been restored after
inflation, axion strings inevitably produce a contribution to the stochastic gravitational wave …

Axion dark matter (DM) may efficiently convert to photons in the magnetospheres of neutron
stars (NSs), producing nearly monochromatic radio emission. This process is resonantly …

The quantum chromodynamics (QCD) axion may solve the strong CP problem and explain
the dark matter (DM) abundance of our Universe. The axion was originally proposed to arise …

Axion strings are horizon-size topological defects that may be produced in the early
Universe. Ultralight axion-like particles may form strings that persist to temperatures below …

Single phonon excitations, with energies in the 1–100 meV range, are a powerful probe of
light dark matter (DM). Utilizing effective field theory, we derive a framework to compute DM …

In these notes I try to introduce the reader to the topic of axions: their theoretical motivation
and expected phenomenology, their role in astrophysics and as dark matter candidate, and …

Existing searches for cosmic axions relics have relied heavily on the axion being
nonrelativistic and making up dark matter. However, light axions can be copiously produced …