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Gauge-invariant perturbations at second order: multiple scalar fields on large scales

Karim A. Malik
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Abstract

We derive the governing equations for multiple scalar fields minimally coupled to gravity in a flat Friedmann-Robertson-Walker (FRW) background spacetime on large scales. We include scalar perturbations up to second order and write the equations in terms of physically transparent gauge-invariant variables at first and second order. This allows us to write the perturbed Klein-Gordon equation at second order solely in terms of the field fluctuations on flat slices at first and second order.

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Karim A. Malik. 2005-11-28. Gauge-invariant perturbations at second order: multiple scalar fields on large scales. https://doi.org/10.1088/1475-7516%2F2005%2F11%2F005

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