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BEGIN:VEVENT
SUMMARY:Saebyeok Jeong (Rutgers U)
DTSTART:20210608T070000Z
DTEND:20210608T083000Z
DTSTAMP:20260422T225847Z
UID:SNUSTRING/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/SNUSTRING/1/
 ">Boundaries\, defects\, and quantization</a>\nby Saebyeok Jeong (Rutgers 
 U) as part of SNU String Seminar\n\n\nAbstract\nAn interesting aspect of f
 our-dimensional N=2 supersymmetric field theories is their correspondence 
 with integrable systems. At the example of class S theories and Hitchin in
 tegrable systems\, I will explain how half-BPS defects in gauge theory can
  be utilized in the quantization problem. More specifically\, the vacuum e
 xpectation values and correlation functions of these defects are exactly c
 omputed by localization\, and analytic constraints make them obey certain 
 differential equations in coupling parameters. These equations and solutio
 ns are interpreted geometrically in the Hitchin moduli space side\, yieldi
 ng various implications on the quantization problem. I will also discuss h
 ow these results can be reformulated in the point of view of the two-dimen
 sional sigma model with the Hitchin target space\, connecting the story to
  that of the N=4 theory of Kapustin-Witten.\n
LOCATION:https://researchseminars.org/talk/SNUSTRING/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Saebyeok Jeong (Rutgers U)
DTSTART:20220802T050000Z
DTEND:20220802T070000Z
DTSTAMP:20260422T225847Z
UID:SNUSTRING/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/SNUSTRING/2/
 ">Fusion of surface defects\, Hecke operator\, and quantum Lax equation</a
 >\nby Saebyeok Jeong (Rutgers U) as part of SNU String Seminar\n\n\nAbstra
 ct\nI will consider a correlation function of two half-BPS surface defects
  in 4d N=2 gauge theory of class S\, which have different 6d origins. I wi
 ll explain their meaning after the reduction to the sigma model on a corne
 r with the Hitchin moduli space target. By localization computation\, we c
 onfirm that the introduction of the second surface defect induces an actio
 n on the parameter space of the first surface defect\, which is shown to b
 e that of the Hecke operator on the conformal block of the vertex algebra 
 at the junction of the corner. Furthermore\, the correlation function is s
 hown to satisfy the 'quantum' Lax equation\, leading to all the mutually c
 ommuting quantum Hamiltonian realized as differential operators acting on 
 the vev of the first surface defect.\n
LOCATION:https://researchseminars.org/talk/SNUSTRING/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Satoshi Yamaguchi (Osaka University)
DTSTART:20230130T050000Z
DTEND:20230130T070000Z
DTSTAMP:20260422T225847Z
UID:SNUSTRING/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/SNUSTRING/3/
 ">Non-invertible symmetries on the lattice (1/2)</a>\nby Satoshi Yamaguchi
  (Osaka University) as part of SNU String Seminar\n\n\nAbstract\nRecently\
 , the study of generalized symmetries and their applications has been rapi
 dly developing. In particular\, examples of a class of generalized symmetr
 y called "non-invertible symmetries" have been found in four dimensions. T
 he key idea in this development is the "topological defects." An approach 
 to such generalized symmetry and  topological defects is through the latti
 ce theory approach developed by Aasen\, Mong\, and Fendley. In this lectur
 e\, I will explain this AMF approach and the generalization to four dimens
 ions done by Koide\, Nagoya\, and myself. I will start with one-dimensiona
 l systems and  explain the relation between classical statistical mechanic
 s and quantum mechanics as well as operators and defects. Then\, I will tu
 rn to two dimensions and explain the Kramerse-Wannier duality and its mani
 festation by non-invertible topological defects. Finally\, I will explain 
 our own work on the topological defects in the four dimensional Z2 lattice
  gauge theory.\n
LOCATION:https://researchseminars.org/talk/SNUSTRING/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Satoshi Yamaguchi (Osaka University)
DTSTART:20230131T050000Z
DTEND:20230131T070000Z
DTSTAMP:20260422T225847Z
UID:SNUSTRING/4
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/SNUSTRING/4/
 ">Non-invertible symmetries on the lattice (2/2)</a>\nby Satoshi Yamaguchi
  (Osaka University) as part of SNU String Seminar\n\n\nAbstract\nRecently\
 , the study of generalized symmetries and their applications has been rapi
 dly developing. In particular\, examples of a class of generalized symmetr
 y called "non-invertible symmetries" have been found in four dimensions. T
 he key idea in this development is the "topological defects." An approach 
 to such generalized symmetry and  topological defects is through the latti
 ce theory approach developed by Aasen\, Mong\, and Fendley. In this lectur
 e\, I will explain this AMF approach and the generalization to four dimens
 ions done by Koide\, Nagoya\, and myself. I will start with one-dimensiona
 l systems and  explain the relation between classical statistical mechanic
 s and quantum mechanics as well as operators and defects. Then\, I will tu
 rn to two dimensions and explain the Kramerse-Wannier duality and its mani
 festation by non-invertible topological defects. Finally\, I will explain 
 our own work on the topological defects in the four dimensional Z2 lattice
  gauge theory.\n
LOCATION:https://researchseminars.org/talk/SNUSTRING/4/
END:VEVENT
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