Nonlinear vector perturbations in a contracting universe

@article{Mena2007NonlinearVP,
  title={Nonlinear vector perturbations in a contracting universe},
  author={Filipe C. Mena and David J. Mulryne and Reza Tavakol},
  journal={Classical and Quantum Gravity},
  year={2007},
  volume={24},
  pages={2721 - 2734}
}
A number of scalar field models proposed as alternatives to the standard inflationary scenario involve contracting phases which precede the universe's present phase of expansion. An important question concerning such models is whether there are effects which could potentially distinguish them from purely expanding cosmologies. Vector perturbations have recently been considered in this context. At first order such perturbations are not supported by a scalar field. In this paper, therefore, we… 

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