Cosmological Perturbations from a New-Physics Hypersurface

TL;DR

This paper examines how initial quantum fluctuations on a new-physics hypersurface influence inflationary cosmological predictions, highlighting the importance of vacuum state definition and adiabatic Hamiltonians in controlling transplanckian effects.

Contribution

It demonstrates that transplanckian effects depend on the choice of vacuum state and can be minimized using adiabatic Hamiltonians, refining previous estimates.

Findings

Transplanckian effects vary with vacuum state definition.

Adiabatic Hamiltonians reduce transplanckian effects.

Proper choice of Hamiltonian minimizes initial quantum fluctuation impacts.

Abstract

Within a broad class of inflationary models we critically analyze the way initial quantum fluctuations on a new-physics hypersurface (NPH) affect standard predictions for large-scale cosmological perturbations. We find that these so-called transplanckian effects depend crucially on the definition of the "vacuum state" in particular on which Hamiltonian is minimized on the NPH in order to select such a state. Transplanckian effects can be made much smaller than previously suggested if sufficiently "adiabatic" Hamiltonians are minimized.