Universal Constraints on Axions from Inflation: Synthetic Tensors and the Scale of Inflation

by Martin Snoager Sloth (CP3-Origins, University of Southern Denmark (DK))

Wednesday 4 Mar 2015, 11:30 → 12:30 Europe/Zurich

4/2-011 - TH common room (CERN)

Much effort is currently spent on trying to detect primordial gravitational waves (tensor modes), or constraining the tensor-to-scalar ratio below the value predicted by many simple and popular models of inflation. A detection of primordial tensor modes would be important, because the amplitude of primordial tensor modes is believed to be directly related to the energy scale of inflation, which is currently unknown. In this cosmo coffee I will discuss the possible caveats to this common belief. Tensor modes can f.ex. be generated through a resonant production of vector fields during inflation from a natural CP-violating axion coupling, and an observable level of primordial tensor modes may therefore not necessary imply a high energy scale of inflation. Tensor modes not related to the scale of inflation are called synthetic tensor modes. I will also discuss some of the finetunings required by an observational signal of synthetic tensor modes, and possible ways of observationally discriminate between synthetic tensor modes and natural tensor modes from inflation.