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Improvement of energy-momentum tensor and non-Gaussianities in holographic cosmology

Kawai, Shinsuke and Nakayama, Yu (2014) Improvement of energy-momentum tensor and non-Gaussianities in holographic cosmology. Journal of High Energy Physics, 2014 (6). Art. No. 052. ISSN 1126-6708. http://resolver.caltech.edu/CaltechAUTHORS:20140707-085226626

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Abstract

In holographic models of cosmology based on the (A)dS/CFT correspondence, conformal symmetry is implicit in the dual description of the Universe. Generically, however, one cannot expect the (broken) conformal invariance in the cosmic fluctuations as only the scale invariance is manifest in experiments. Also, in order for the prediction of the holographic models to make sense, the conformal symmetry needs to be broken as the scalar mode of the metric fluctuations becomes pure gauge in the conformal limit. We discuss the improvement ambiguity of the energy-momentum tensor in this context and construct a holographic model of the Universe that preserves the scale invariance but not necessarily the full conformal invariance. Our sample computation using a weakly coupled dual field theory shows that the orthogonal type of non-Gaussianity is present over and above the equilateral type. The improvement ambiguity corresponds to the choice of the energy momentum tensor that will couple to our particle physics sector after inflation. Our results show that the holographic prediction of the cosmological parameters crucially depends on such a choice.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://arxiv.org/abs/1403.6220arXivDiscussion Paper
http://dx.doi.org/10.1007/JHEP06(2014)052DOIArticle
http://link.springer.com/article/10.1007%2FJHEP06%282014%29052PublisherArticle
Additional Information:© 2014 The Authors. Published for SISSA by Springer. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited. Article funded by SCOAP3. Received: April 6, 2014; Accepted: May 19, 2014; Published: June 10, 2014. We acknowledge helpful conversations with Gary Shiu and Toshifumi Noumi. S.K. acknowledges warm hospitality of the Kavli IPMU, the University of Tokyo where the final stage of this work was carried out. He also thanks Paul McFadden for sharing unpublished lecture notes. This work is supported in part by the Sherman Fairchild Senior Research Fellowship at California Institute of Technology with DOE grant DE-FG02-92ER40701 and the World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan (Y.N.), and by the National Research Foundation of Korea Grant-in-Aid for Scientific Research No. 2013028565 (S.K.).
Group:Caltech Theory
Funders:
Funding AgencyGrant Number
Sherman Fairchild FoundationUNSPECIFIED
Department of Energy (DOE)DE-FG02-92ER40701
World Premier International Research Center Initiative (WPI Initiative), MEXT, JapanUNSPECIFIED
National Research Foundation of Korea Grant-in-Aid for Scientific Research2013028565
Subject Keywords:Cosmology of Theories beyond the SM; Models of Quantum Gravity; Gauge-gravity correspondence; AdS-CFT Correspondence
Record Number:CaltechAUTHORS:20140707-085226626
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140707-085226626
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46868
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Jul 2014 16:06
Last Modified:29 Aug 2014 14:27

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