Scalar perturbations during multiple-field slow-roll inflation

By S. G. Nibbelink, B. Tent. 2001

281 citations recorded by the source corpus.

We calculate the scalar gravitational and matter perturbations in the context of slow-roll inflation with multiple scalar fields, that take values on a (curved) manifold, to first order in slow roll. For this purpose a basis for these perturbations determined by the background dynamics is introduced and multiple-field slow-roll functions are defined. To obtain analytical solutions to first order, the scalar perturbation modes have to be treated in three different regimes. Matching is performed by identifying leading order asymptotic expansions analytically in different regions. The possible sources for multiple-field effects in the gravitational potential are the particular solution caused by the coupling to the field perturbation perpendicular to the field velocity, and the rotation of the basis. The former can contribute even to leading order if the corresponding multiple-field slow-roll function is sizable during the last 60 e-folds. Making some simplifying assumptions, the evolution of adiabatic and isocurvature perturbations after inflation is discussed. The analytical results are illustrated and checked numerically with the example of a quadratic potential.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1e0ca7e17b23c50f5447b6bc1ba536b9a0549d0a

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In Astronomy and Astrophysics

1. Yi Wang
2. D. Baumann
3. Xingang Chen
4. S. Patil
5. Toshifumi Noumi
6. D. Yokoyama
7. D. Seery
8. G. Palma

Citations in the corpus

• Effective theories of single field inflation when heavy fields matter (2012, unknown): “[46, 47], and its notation stems from the definition of a vector η ≡ −φ̈a0/(Hφ̇0) [48] in order to extend the definition of the usual η parameter to the multi-field case.”
• Inflation, Cosmic Perturbations and Non-Gaussianities (2013, methodology): “We can rotate the basis in the field space of those fields, such that there is only one rolling field [168, 169].”
• Effective field theory approach to quasi-single field inflation and effects of heavy fields (2012, background): “This class of models were carefully studied in [42] and recently discussed in [22] to investigate effects of massive particles during inflation.”
• Primordial non-Gaussianities from multiple-field inflation (2005, background): “covers a very wide class of multi-field inflationary models, it would be interesting to go beyond this approximation (see, for example, [68, 45, 50 , 51]).”
• Oscillations in the stochastic gravitational wave background from sharp features and particle production during inflation (2020, background): “It indeed measures the amount of deviation of the background trajectory from a field space geodesic [30, 31], or equivalently the acceleration of the trajectory perpendicular to its velocity.”
• Features of heavy physics in the CMB power spectrum (2010, background): “The discussion in the sequel follows closely the analysis in [37, 38].”