Phenomenology of Axion-Gauge Interactions in the Early Universe

by Alexandros Papageorgiou (University of Minnesota)

Wednesday 18 Aug 2021, 16:30 → 18:30 Europe/Zurich

CERN

In this talk I will present various effects that arise as a consequence of axion-gauge couplings both in the context of inflation as well as dark energy. Axions (or Axion-Like Particles) are pseudo-scalar particles that enjoy an approximate shift symmetry which protects the flatness of their potential from obtaining large radiative corrections. This makes axions ideal candidates for the inflaton or quintessence fields. Couplings of axions to gauge fields can lead to interesting results that involve baryogenesis, sourced gravitational waves and/or large nonlinear contributions to scalar perturbations. In the context of dark energy, axion gauge couplings may lead to observationally acceptable quintessence, even for a steep potential as a result of the axion field producing the gauge field at the expense of its own kinetic energy. This may lead to resolving the tension between observations and the swampland conjecture on the slope of the quintessence field.