Abstract
Functional renormalization group equations are analytically continued from imaginary Matsubara frequencies to the real frequency axis. On the example of a scalar field with \( \mathcal{O} \)(N) symmetry we discuss the analytic structure of the flowing action and show how it is possible to derive and solve flow equations for real-time properties such as propagator residues and particle decay widths. The formalism conserves space-time symmetries such as Lorentz or Galilei invariance and allows for improved, self-consistent approximations in terms of derivative expansions in Minkowski space.
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Floerchinger, S. Analytic continuation of functional renormalization group equations. J. High Energ. Phys. 2012, 21 (2012). https://doi.org/10.1007/JHEP05(2012)021
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DOI: https://doi.org/10.1007/JHEP05(2012)021