MG12 - Talk detail
 

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Abstract

Gauge-invariant backreaction in growing-curvature cosmologies

I will show how to provide suitable gauge invariant prescriptions for quantum expectation values of amplified cosmological perturbations. I will apply such prescriptions to the computation of backreaction effects in the context of growing curvature cosmological backgrounds, such as pre-big bang and ekpyrotic scenarios. In that context the backreaction of fluctuations could be important for avoiding the big bang singularity and implementing a smooth graceful exit towards the epoch of standard (post-big bang) cosmological evolution. I will also explain how the use of naive prescriptions can lead to gauge artefacts and ambiguous interpretations. Based on: M. Gasperini, G.Marozzi and G. Veneziano, JCAP 03 (2009) 011. M. Gasperini, G.Marozzi and G. Veneziano, to appear.

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