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SUMMARY:Kirill Semenov-Tian-Shansky (Kurchatov Institute)
DTSTART:20210930T073000Z
DTEND:20210930T083000Z
DTSTAMP:20260423T024727Z
UID:ttbar2021/9
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/ttbar2021/9/
 ">Elliptic functions and exact summation of leading logs around $T\\bar{T}
 $ deformation of $O(N+1)$-symmetric 2D QFTs</a>\nby Kirill Semenov-Tian-Sh
 ansky (Kurchatov Institute) as part of Exact Results on Irrelevant Deforma
 tions of QFTs\n\n\nAbstract\nIn this talk we consider the most general (be
 yond $T\\bar{T}$) deformation of the  $2D$ $O(N+1)$ $\\sigma$-model by th
 e irrelevant dimension-four operators.  The theory deformed in this way i
 s generally not integrable\, and its $S$-matrix loses the factorization pr
 operties.  We present an overview of the method of exact all-order summat
 ion of leading infrared  logarithms in $2D$ massless $\\phi^4$-type non-r
 enormalizable effective field theories (EFTs).  It is based on the fundam
 ental requirements of unitarity\, analyticity and crossing symmetry of sca
 ttering amplitudes and generalizes the renormalization group technique for
  the case of non-renormalizable EFTs.   This method allows us to provide 
 the exact results for the  $2 \\to 2$ $S$-matrix in the leading logarithm
 ic  approximation in the deformed $2D$ $O(N+1)$ $\\sigma$-model. In parti
 cular\, we present the remarkable solution  expressed in terms of ellipti
 c functions leading to scattering amplitudes with a doubly periodic struct
 ure of the Landau  poles. We discuss the new insights into the properties
  of the theories deformed by irrelevant operators more general than  the 
 $T\\bar{T}$ deformation from the perspective of our approach.TBA\n
LOCATION:https://researchseminars.org/talk/ttbar2021/9/
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