THE ROBUSTNESS OF INFLATION TO CHANGES IN SUPER-PLANCK-SCALE PHYSICS

By Robert Brandenberger, Jérôme Martin. 2000

289 citations recorded by the source corpus.

We calculate the spectrum of density fluctuations in models of inflation based on a weakly self-coupled scalar matter field minimally coupled to gravity, and specifically investigate the dependence of the predictions on modifications of the physics on length scales smaller than the Planck length. These modifications are encoded in terms of modified dispersion relations. Whereas for some classes of dispersion relations the predictions are unchanged compared to the usual ones which are based on a linear dispersion relation, for other classes important differences are obtained, involving tilted spectra, spectra with exponential factors and with oscillations. This is the case when the dispersion relation becomes complex. We conclude that the predictions of inflationary cosmology in these models are not robust against changes in the super-Planck-scale physics.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/3bf7d28dd1ca4f6a14e0865dbb0a0a6c56840985

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Citations in the corpus

Signatures of short distance physics in the cosmic microwave background (2002, background): “Several groups [7,8,9,10,11] have studied the effect that simple phenomenological models of stringy corrections to gravity would have on the inflationary fluctuation spectrum in the CMBR.”
Initial Conditions for Inflation (2002, background): “But as pointed out in [16], the quantum states advocated by [1,4,5,13,14] as an initial state for inflation lie in a one-parameter family of de Sitterinvariant states, constructed and described in [17,18,19,20].”
Quantum-Spacetime Phenomenology (2008, background): “Many of these studies [136, 172, 410, 217, 266, 198, 321, 274] have probed the possibility that a short-distance cutoff might leave a trace in cosmology measurements such as the ones conducted on the cosmic microwave background.”
Inflation, Cosmic Perturbations and Non-Gaussianities (2013, background): “• The trans-Planckian problem [57–59]: Comoving scales expand exponentially during inflation.”
Matter bounce in Horava-Lifshitz cosmology (2009, background): “In [6] it was emphasized that if the wavelength of fluctuations penetrates the UV region, then the usual arguments for the origin of a scale-invariant spectrum of cosmological perturbations from an inflationary phase might break down, as suggested more generally in the context of the “trans-Planckia”
Inflation, holography, and the choice of vacuum in de Sitter space (2002, background): “In several recent works the rationality of this assumption has been questioned, [2-26].”
Are inflationary predictions sensitive to very high energy physics (2002, background): “(This is in agreement with the results of Martin and Brandenberger [ 1 ], but by disentangling the adiabaticity from more exotic possibilities like non-Lorentz-invariant dispersion relations we also show that these exotic assumptions are not crucial for obtaining an observable effect.) The relevance”
Analogue Gravity (2005, background): “We expect that these analogue models provide us with new insights as to how their inherent modified dispersion relations affect cosmological process such as the generation of a primordial spectrum of perturbations (see for example [250, 251, 46, 42, 41, 107, 209, 229, 230, 249, 275, 275, 274, 43, 47”
Trans-Planckian issues for inflationary cosmology (2012, methodology): “However, in models in which non-adiabaticity is violated at all UV scales (like the ones considered in [19]), short wavelength modes spend more time in the region of non-adiabaticity, and hence the spectrum of cosmological perturbations will acquire a blue tilt whose spectral slope can well exceed c”