Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem
| Autor: | Li, Yu-Bin, Quintin, Jerome, Wang, Dong-Gang, Cai, Yi-Fu |
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| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | JCAP03(2017)031 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/1475-7516/2017/03/031 |
| Popis: | 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. Comment: 23 pages, 1 figure; v2: references added; v3: minor changes, minor typos corrected, references added, matches published version |
| Databáze: | arXiv |
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