Complex Path Integrals and Saddles in Two-Dimensional Gauge Theory

Dec 30, 2015
5 pages
Published in:
  • Phys.Rev.Lett. 116 (2016) 13, 132001
  • Published: Mar 30, 2016
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Abstract: (APS)
We study numerically the saddle point structure of two-dimensional lattice gauge theory, represented by the Gross-Witten-Wadia unitary matrix model. The saddle points are, in general, complex valued, even though the original integration variables and action are real. We confirm the trans-series and instanton gas structure in the weak-coupling phase, and we identify a new complex-saddle interpretation of nonperturbative effects in the strong-coupling phase. In both phases, eigenvalue tunneling refers to eigenvalues moving off the real interval, into the complex plane, and the weak-to-strong coupling phase transition is driven by saddle condensation.
Note:
  • 4+4 pages RevTeX, 9 figures; v2: version published in PRL
  • 12.38.Aw
  • 02.10.Yn
  • matrix model: unitarity
  • effect: nonperturbative
  • instanton: gas
  • lattice field theory
  • critical phenomena
  • gauge field theory
  • strong coupling
  • weak coupling