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 …

Gravitational waves (GWs) have a great potential to probe cosmology. We review early
universe sources that can lead to cosmological backgrounds of GWs. We begin by …

We present results from an analysis of all data taken by the BICEP2, Keck Array, and
BICEP3 CMB polarization experiments up to and including the 2018 observing season. We …

We revisit the possibility that the stochastic common-spectrum process recently detected by
the NANOGrav pulsar timing array experiment could be due to primordial gravitational …

We report on the implications for cosmic inflation of the 2018 release of the Planck cosmic
microwave background (CMB) anisotropy measurements. The results are fully consistent …

We present the temperature and polarization angular power spectra of the CMB measured
by the Atacama Cosmology Telescope (ACT) from 5400 deg 2 of the 2013–2016 survey …

We present cosmological parameter results from the final full-mission Planck measurements
of the cosmic microwave background (CMB) anisotropies, combining information from the …

We present results from an analysis of all data taken by the bicep2/Keck CMB polarization
experiments up to and including the 2015 observing season. This includes the first Keck …

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 …

TianQin is a proposal for a space-borne detector of gravitational waves in the millihertz
frequencies. The experiment relies on a constellation of three drag-free spacecraft orbiting …