Novel quantum initial conditions for inflation

Abstract

We present a novel approach for setting initial conditions on the mode functions of the Mukhanov-Sasaki equation. These conditions are motivated by minimization of the renormalized stress-energy tensor and are valid for setting a vacuum state even in a context where the spacetime is changing rapidly. Moreover, these alternative conditions are potentially observationally distinguishable. We apply this to the kinetically dominated universe and compare with the more traditional approach.