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Title: Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem

Abstract

We extend the matter bounce scenario to a more general theory in which the background dynamics and cosmological perturbations are generated by a k -essence scalar field with an arbitrary sound speed. When the sound speed is small, the curvature perturbation is enhanced, and the tensor-to-scalar ratio, which is excessively large in the original model, can be sufficiently suppressed to be consistent with observational bounds. Then, we study the primordial three-point correlation function generated during the matter-dominated contraction stage and find that it only depends on the sound speed parameter. Similar to the canonical case, the shape of the bispectrum is mainly dominated by a local form, though for some specific sound speed values a new shape emerges and the scaling behaviour changes. Meanwhile, a small sound speed also results in a large amplitude of non-Gaussianities, which is disfavored by current observations. As a result, it does not seem possible to suppress the tensor-to-scalar ratio without amplifying the production of non-Gaussianities beyond current observational constraints (and vice versa). This suggests an extension of the previously conjectured no-go theorem in single field nonsingular matter bounce cosmologies, which rules out a large class of models. However, the non-Gaussianity results remain as amore » distinguishable signature of matter bounce cosmology and have the potential to be detected by observations in the near future.« less

Authors:
;  [1];  [2];  [3]
  1. CAS Key Laboratory for Researches in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China)
  2. Department of Physics, McGill University, 3600 rue University, Montréal, QC, H3A 2T8 (Canada)
  3. Leiden Observatory, Leiden University, 2300 RA Leiden (Netherlands)
Publication Date:
OSTI Identifier:
22679973
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 03; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; CORRELATION FUNCTIONS; CORRELATIONS; COSMOLOGY; DISTURBANCES; PERTURBATION THEORY; SCALAR FIELDS; VELOCITY

Citation Formats

Li, Yu-Bin, Cai, Yi-Fu, Quintin, Jerome, and Wang, Dong-Gang, E-mail: lyb2166@mail.ustc.edu.cn, E-mail: jquintin@physics.mcgill.ca, E-mail: wdgang@strw.leidenuniv.nl, E-mail: yifucai@ustc.edu.cn. Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem. United States: N. p., 2017. Web. doi:10.1088/1475-7516/2017/03/031.
Li, Yu-Bin, Cai, Yi-Fu, Quintin, Jerome, & Wang, Dong-Gang, E-mail: lyb2166@mail.ustc.edu.cn, E-mail: jquintin@physics.mcgill.ca, E-mail: wdgang@strw.leidenuniv.nl, E-mail: yifucai@ustc.edu.cn. Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem. United States. doi:10.1088/1475-7516/2017/03/031.
Li, Yu-Bin, Cai, Yi-Fu, Quintin, Jerome, and Wang, Dong-Gang, E-mail: lyb2166@mail.ustc.edu.cn, E-mail: jquintin@physics.mcgill.ca, E-mail: wdgang@strw.leidenuniv.nl, E-mail: yifucai@ustc.edu.cn. Wed . "Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem". United States. doi:10.1088/1475-7516/2017/03/031.
@article{osti_22679973,
title = {Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem},
author = {Li, Yu-Bin and Cai, Yi-Fu and Quintin, Jerome and Wang, Dong-Gang, E-mail: lyb2166@mail.ustc.edu.cn, E-mail: jquintin@physics.mcgill.ca, E-mail: wdgang@strw.leidenuniv.nl, E-mail: yifucai@ustc.edu.cn},
abstractNote = {We extend the matter bounce scenario to a more general theory in which the background dynamics and cosmological perturbations are generated by a k -essence scalar field with an arbitrary sound speed. When the sound speed is small, the curvature perturbation is enhanced, and the tensor-to-scalar ratio, which is excessively large in the original model, can be sufficiently suppressed to be consistent with observational bounds. Then, we study the primordial three-point correlation function generated during the matter-dominated contraction stage and find that it only depends on the sound speed parameter. Similar to the canonical case, the shape of the bispectrum is mainly dominated by a local form, though for some specific sound speed values a new shape emerges and the scaling behaviour changes. Meanwhile, a small sound speed also results in a large amplitude of non-Gaussianities, which is disfavored by current observations. As a result, it does not seem possible to suppress the tensor-to-scalar ratio without amplifying the production of non-Gaussianities beyond current observational constraints (and vice versa). This suggests an extension of the previously conjectured no-go theorem in single field nonsingular matter bounce cosmologies, which rules out a large class of models. However, the non-Gaussianity results remain as a distinguishable signature of matter bounce cosmology and have the potential to be detected by observations in the near future.},
doi = {10.1088/1475-7516/2017/03/031},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 03,
volume = 2017,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}