Speaker
Description
Effective field theory techniques provide an efficient way to enumerate the allowed operators in various physical systems based on their symmetries. Moreover, they allow for a systematic classification of these operators in decreasing order of relevance based on a derivative expansion. These tools are powerful in guiding us towards the construction of a realistic inflationary scenario with few model assumptions. In this presentation, I will guide the audience towards more general effective field theories of inflationary fluctuations than what is usually considered. In particular, I will show how nonlinearly realised symmetries play a key role in multifield inflation, and I will make the explicit link with the theory for fluctuations in nonlinear sigma models. Finally, I will present a few interesting features at the one-loop level, where symmetries beautifully restore the conservation of the primordial curvature perturbation on super-Hubble scales.