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Inflationary perturbations with multiple scalar fields

B. J. W. van Tent·S. Groot Nibbelink
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Abstract

The calculation of scalar gravitational and matter perturbations during multiple-field inflation valid to first order in slow roll is discussed. These fields may be the coordinates of a non-trivial field manifold and hence have non-minimal kinetic terms. A basis for these perturbations determined by the background dynamics is introduced, and the slow-roll functions are generalized to the multiple-field case. Solutions for a perturbation mode in its three different behavioural regimes are combined, leading to an analytic expression for the correlator of the gravitational potential. Multiple-field effects caused by the coupling to the field perturbation perpendicular to the field velocity can even contribute at leading order. This is illustrated numerically with an example of a quadratic potential. (The material here is based on previous work by the authors presented in hep-ph/0107272.)

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B. J. W. van Tent, S. Groot Nibbelink. 2001-11-28. Inflationary perturbations with multiple scalar fields. https://arxiv.org/abs/hep-ph/0111370

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