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SUMMARY:Resurgence in QFT  -renormalon\, phase transition and more- - Tats
 uhiro Misumi (Kindai University)
DTSTART:20221216T100000Z
DTEND:20221216T110000Z
UID:TALK193304@talks.cam.ac.uk
DESCRIPTION:We discuss the resurgent structure of quantum field theory\, w
 ith emphasis on IR-renormalon and phase transition. We study the 2D sigma 
 models at large N\, with an IR momentum cutoff scale A introduced to regul
 arize IR singularities in the trans-series expression. Trans-series expres
 sions for physical quantities are derived as series of the dynamical scale
  \\Lambda and coupling \\lambda. While there is no ambiguity when A > \\La
 mbda\, we find for A < \\Lambda that the nonperturbative sectors have new 
 imaginary ambiguities besides the well-known renormalon ambiguity in the p
 erturbative sector\, which arise as a result of an analytic continuation o
 f trans-series coefficients to A < \\Lambda. We show that the renormalon i
 maginary ambiguity is cancelled by the combined imaginary ambiguities at t
 he different orders of \\Lambda in the trans-series. We find in the compac
 tified model with the ZN twisted boundary condition that the resurgence st
 ructure changes discontinuously as the compactification radius is varied. 
 We also discuss the nontrivial relation between the order of phase transit
 ion and the behavior of Borel singularities.&nbsp\;
LOCATION:Seminar Room 1\, Newton Institute
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