8 papers
A scaling non-compact QCD axion
Georgios K. Karananas, Mikhail Shaposhnikov
We present a dynamical mechanism for the erasure of inflationary isocurvature perturbations of the non-compact QCD axion. The key ingredient is an early-time runaway exponential po…
QCD axion from broken scale symmetry
Georgios K. Karananas, Mikhail Shaposhnikov
A consistent non-compact axion cosmology requires a non-periodic field, an effective field theory valid sufficiently above the inflationary scale, and a small non-QCD contribution…
Three-form lifting of dilaton flat direction without and with gravity
Georgios K. Karananas
Spontaneous scale symmetry breaking is commonly associated with a flat direction in the action. We show that this need not be so if the dilaton is coupled to a three-form field in…
A non-compact QCD axion
Georgios K. Karananas, Mikhail Shaposhnikov, Sebastian Zell
We investigate the cosmology of an axion that is fundamentally non-compact. During inflation, fluctuations of the effectively massless field populate many QCD vacua, thereby evadin…
Higgs inflation in Weyl-invariant Einstein-Cartan gravity
Georgios K. Karananas, Mikhail Shaposhnikov
In this short note we analyze the inflationary dynamics in Weyl-invariant Einstein-Cartan gravity coupled to the Standard Model of particle physics. We take the axion-like particle…
On the Gravitational Origin of the QCD Axion
Georgios K. Karananas, Mikhail Shaposhnikov, Sebastian Zell
Gravity can give rise to (pseudo)scalar fields, for instance due to torsion. In particular, axions of gravitational origin have been proposed as a minimal and compelling solution t…