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SUMMARY:The 2-dimensional O(N) sigma model: a resurgence laboratory - Jano
 s Balog (WIGNER Research Centre for Physics)
DTSTART:20220913T123000Z
DTEND:20220913T133000Z
UID:TALK178109@talks.cam.ac.uk
DESCRIPTION:We study the solution of the TBA integral equation describing 
 the energy density of finite density states in the 1+1 dimensional O(N) no
 n-linear sigma model by the Wiener-Hopf method. Using Volin's algorithm we
  determine the asymptotic series expansion of the energy density in powers
  of a non-perturbative running coupling to very large orders. We calculate
  the first 2000 terms of the series for the N=4 case\, which allows us to 
 determine the first few alien derivatives of the perturbative series. We s
 how that (at least in this case) resurgence theory works in its strongest 
 version: the physical resummation of the perturbative series is given by t
 he median resummation and this agrees with the result of the original exac
 t TBA equation. For the O(3) case we calculate the 1- and 2-instanton cont
 ributions perturbatively to very large orders.
LOCATION:No Room Required
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