The Power of Perturbation Theory. Serone, M., Spada, G., & Villadoro, G. , 2, 2017.
The Power of Perturbation Theory [link]Paper  doi  abstract   bibtex   
We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the Picard-Lefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented.
@article{Serone-2017-ID296,
  title     = {The Power of Perturbation Theory},
  abstract  = {We study quantum mechanical systems with a discrete spectrum. We show that
               the asymptotic series associated to certain paths of steepest-descent
               (Lefschetz thimbles) are Borel resummable to the full result. Using a
               geometrical approach based on the Picard-Lefschetz theory we characterize
               the conditions under which perturbative expansions lead to exact results.
               Even when such conditions are not met, we explain how to define a different
               perturbative expansion that reproduces the full answer without the need of
               transseries, i.e. non-perturbative effects, such as real (or complex)
               instantons. Applications to several quantum mechanical systems are
               presented.},
  author    = {Serone, Marco and Spada, Gabriele and Villadoro, Giovanni},
  journal   = {},
  year      = {2017},
  month     = {2},
  url       = {http://arxiv.org/abs/1702.04148v2},
  url       = {http://arxiv.org/pdf/1702.04148v2},
  arxiv     = {1702.04148v2},
  doi       = {10.1007/JHEP05(2017)056},
  keywords  = {hep-th},
  file      = {FULLTEXT:pdfs/000/000/000000296.pdf:PDF}
}

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