Cosmology with negative potentials

@article{Felder2002CosmologyWN,
  title={Cosmology with negative potentials},
  author={Gary N. Felder and Andrei V. Frolov and Lev Kofman and Andrei Linde},
  journal={Physical Review D},
  year={2002},
  volume={66}
}
We investigate cosmological evolution in models where the effective potential $V(\ensuremath{\varphi})$ may become negative for some values of the field $\ensuremath{\varphi}.$ Phase portraits of such theories in the space of variables $(\ensuremath{\varphi},\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{\ensuremath{\varphi}},H)$ have several qualitatively new features as compared with phase portraits in the theories with $V(\ensuremath{\varphi})g0.$ Cosmological evolution in models with potentials… 

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