Abstract
The inflationary cosmology paradigm is very successful in explaining the CMB anisotropy to the percent level.Besides the dependence on the inflationary model, the power spectra, spectral tilt and non-Gaussianity of the CMB temperature fluctuations also depend on the initial state of inflation. Here, we examine to what extent these observables are affectedby our ignorance in the initial condition for inflationary perturbations, due to unknownnew physics at a high scale M. For initial states that satisfy constraints from backreaction, we find that the amplitude of the power spectra could still be significantly altered, while the modification in bispectrum remains small. For such initial states, M has an upper bound of a few tens of H, with H being the Hubble parameter during inflation. We show that for M ∼ 20H, suchinitial states always (substantially) suppress the tensor to scalar ratio. In particular we show that such a choice of initial conditions can satisfactorily reconcile the simple ½m2ϕ2 chaotic model with the Planck data [1-3].
Highlights
The increasingly precise CMB measurements by Planck mission in combination with other cosmological date have ushered us into a precision early Universe cosmology era: log ≡ log
Quantum fluctuation are stretched to cosmological size due to the quasiexponential expansion of inflation
Predictions of inflationary models for the CMB temperature fluctuations depend on the initial condition for fluctuations too
Summary
The increasingly precise CMB measurements by Planck mission in combination with other cosmological date have ushered us into a precision early Universe cosmology era: log ≡ log. One explanation for lack of observation of tensor modes is that gravity is a classical field!. Steinhardt, Loeb (2013) argue that convex models like region (a) is more likely to cause inflation. Decays like decays like constant (a) (b) comes to dominate the universe and slow‐roll inflation starts
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