Non-Gaussianity from excited initial inflationary states

We study squeezed limit fNL generation by excited initial inationary states in a model independent way. We restrict \excited" to mean a Bogoliubov trans- formation of the Bunch Davies state. We simultaneously impose the constraints that the observable power spectrum is nearly scale invariant over at least three decades and that the observable modes today be subhorizon at the beginning of ination while not causing signicant backreaction. We show that most excited initial inationary states for single eld inationary models with negligible superhorizon evolution do not pro- duce an observable squeezed limit fNL. The case in which one mode is in the Bunch Davies state while the other two modes are in an excited state with 0:01

Keywords:

• Quantum electrodynamics
• Observable
• Scaling
• Excited state
• Spectral density
• Scale invariance
• Non-Gaussianity
• Bispectrum
• Back-reaction
• Physics

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