Conformal invariance and the four point scalar correlator in slow-roll inflation

Archisman Ghosh (International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, IISc Campus, Bangalore 560012, India) ; Nilay Kundu (Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Colaba, Mumbai 400 005, India) ; Suvrat Raju (International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, IISc Campus, Bangalore 560012, India) ; Sandip P. Trivedi (Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Colaba, Mumbai 400 005, India)

We calculate the four point correlation function for scalar perturbations in the canonical model of slow-roll inflation. We work in the leading slow-roll approximation where the calculation can be done in de Sitter space. Our calculation uses techniques drawn from the AdS/CFT correspondence to find the wave function at late times and then calculate the four point function from it. The answer we get agrees with an earlier result in the literature, obtained using different methods. Our analysis reveals a subtlety with regard to the Ward identities for conformal invariance, which arises in de Sitter space and has no analogue in AdS space. This subtlety arises because in de Sitter space the metric at late times is a genuine degree of freedom, and hence to calculate correlation functions from the wave function of the Universe at late times, one must fix gauge completely. The resulting correlators are then invariant under a conformal transformation accompanied by a compensating coordinate transformation which restores the gauge.

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Published on:
01 July 2014
Publisher:
Springer/SISSA
Published in:
Journal of High Energy Physics (2014)

DOI:
https://doi.org/10.1007/JHEP07(2014)011
arXiv:
1401.1426
Copyrights:
The Author(s)
Licence:
CC-BY-4.0

Fulltext files: