Bootstrapping Cosmological Correlators

Abstract

Both Conformal and Boostless Bootstrap techniques have been applied by many in the literature to compute pure scalar and graviton inflationary correlators. In this thesis, our focus will primarily be on mixed graviton and scalar correlators. We start by reviewing single-field inflation and then move ahead to developing an EFT of Inflation (EFToI) with some general assumptions, clarifying various subtleties related to power counting. We verify explicitly the soft limits for mixed correlators, showing how they are satisfied for higher derivative operators beyond the Maldacena action. We clarify some confusion in the literature related to the soft limits for operators that modify the power spectra of gravitons or scalars. We then proceed to apply the boostless bootstrap rules to operators that do not modify the power spectra. Towards the end, we give a prescription that gives correlators for alpha vacua directly once we have the correlator for the Bunch-Davies vacuum. This enables us to bypass complicated in-in calculations for alpha vacua.