|| Title: How to Constrain Inflation as an Effective Field Theorist
Not all field theories are good theories. In particular, a good field
theory Lagrangian should be stable (against quantum corrections),
predictive (give well-defined transition probabilities), and
UV-completable (can make sense at high energies).
For Lorentz-invariant systems, we know how to build effective field
theories with these properties – namely through implementing a power
counting scheme, perturbative unitarity constraints, and positivity
bounds. But during inflation, Lorentz symmetry is spontaneously broken
by the background (there is a preferred reference frame in which the
expansion of the background spacetime is spatially isotropic).
In this talk, I will describe how to import the techniques for
constructing good Lorentz-invariant field theories to settings in which
Lorentz symmetry is broken. This provides a new set of theoretical
constraints on the Effective Field Theory of Inflation, which complement
ongoing observational searches for primordial non-Gaussianity. ||