Unstable growth of curvature perturbations in nonsingular bouncing cosmologies |
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Authors: | Xue BingKan Steinhardt Paul J |
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Institution: | Department of Physics, Princeton University, Princeton, New Jersey 08544, USA. |
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Abstract: | Bouncing cosmologies require an ekpyrotic contracting phase (w?1) in order to achieve flatness, homogeneity, and isotropy. Models with a nonsingular bounce further require a bouncing phase that violates the null energy condition (w<-1). We show that the transition from the ekpyrotic phase to the bouncing phase creates problems for cosmological perturbations. 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. |
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