paper

Non-singular Ekpyrotic/Cyclic model in Loop Quantum Cosmology

arXiv:0907.5591 · doi:10.1103/PhysRevD.80.124013

Abstract

We study the role of non-perturbative quantum gravity effects in the Ekpyrotic/Cyclic model using the effective framework of loop quantum cosmology in the presence of anisotropies. We show that quantum geometric modifications to the dynamical equations near the Planck scale as understood in the quantization of Bianchi-I spacetime in loop quantum cosmology lead to the resolution of classical singularity and result in a non-singular transition of the universe from the contracting to the expanding branch. In the Planck regime, the universe undergoes multiple small bounces and the anisotropic shear remains bounded throughout the evolution. A novel feature, which is absent for isotropic models, is a natural turn around of the moduli field from the negative region of the potential leading to a cyclic phenomena as envisioned in the original paradigm. Our work suggests that incorporation of quantum gravitational effects in the Ekpyrotic/Cyclic model may lead to a viable scenario without any violation of the null energy condition.

24 pages, 11 figures. Additional numerical results discussed to show robustness of non-singular bounce of the scale factor and turn-around of the moduli field. References added. To appear in Physical Review D

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