Reconciliation of high energy scale models of inflation with Planck

Ashoorioon, Amjad and Dimopoulos, Konstantinos and M. Sheikh-Jabbari, Mohammad and Shiu, Gary (2014) Reconciliation of high energy scale models of inflation with Planck. Journal of Cosmology and Astroparticle Physics, 2014 (2): 025. ISSN 1475-7516

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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 affected by our ignorance in the initial condition for inflationary perturbations, due to unknown new 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 signifcantly altered, while the modifcation 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, such initial 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 quadratic chaotic model with the Planck data.