2010

Unstable growth of curvature perturbation in non-singular bouncing cosmologies

Xue, BingKan, Steinhardt, Paul J.

Understand

We consider non-singular bouncing cosmologies, such as the new ekpyrotic model, in which the universe undergoes a slow contraction phase with equation of state $w \gg 1$, followed by a bounce that occurs at a finite scale factor when quantum gravity corrections are still negligible.

Such a non-singular bounce requires a violation of the null energy condition in which $w$ falls below -1 at some time before the bounce.
In this paper, we show that a component of the adiabatic curvature perturbations, though decaying and negligible during the ekpyrotic phase, is exponentially amplified just before $w$ approaches -1, enough to spoil the scale-invariant perturbation spectrum.
We discuss how the problem may be avoided, for example, in singular bounces.

Built on

J. Khoury, B. A. Ovrut, P. J. Steinhardt and N. Turok, Phys. Rev. D 64
2001
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J. Khoury, B. A. Ovrut, N. Seiberg, P. J. Steinhardt and N. Turok, Phys. Rev. D 65
2002
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J. K. Erickson, D. H. Wesley, P. J. Steinhardt and N. Turok, Phys. Rev. D 69
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N. Arkani-Hamed, H. C. Cheng, M. A. Luty and S. Mukohyama, JHEP 0405
2004
Earlier work this paper cites.

Similar

P. Creminelli, M. A. Luty, A. Nicolis and L. Senatore, JHEP 0612
2006
Cited alongside, same era.
E. I. Buchbinder, J. Khoury and B. A. Ovrut, Phys. Rev. D 76
2007
Cited alongside, same era.
J. L. Lehners, P. McFadden, N. Turok and P. J. Steinhardt, Phys. Rev. D 76
2007
Cited alongside, same era.
P. Creminelli and L. Senatore, JCAP 0711
2007
Cited alongside, same era.
B.K. Xue, in preparation
Cited in the paper.
J. Khoury and P. J. Steinhardt, arXiv:0910.2230 [hep-th]
Original
Cited in the paper.
J. Khoury, P. J. Steinhardt, and B.K. Xue, forthcoming
Original
Cited in the paper.

Then

J. L. Lehners, Phys. Rept. 465
Original
2008
Later among the works it cites.
C. Gordon, D. Wands, B. A. Bassett and R. Maartens, Phys. Rev. D 63
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2008
Later among the works it cites.
There has been some debate about whether the ghost condensate mechanism can be implemented in a self-consistent low-energy effective theory; see R. Kallosh, J. U. Kang, A. D. Linde and V. Mukhanov, JCAP 0804
Original
2009
Later among the works it cites.

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