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SUMMARY:Christophe Garban (Lyon)
DTSTART:20210205T173000Z
DTEND:20210205T183000Z
DTSTAMP:20260423T005653Z
UID:PatC/26
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/PatC/26/">Vo
 rtex fluctuations in continuous spin systems and lattice gauge theory</a>\
 nby Christophe Garban (Lyon) as part of Probability and the City Seminar\n
 \n\nAbstract\nTopological phase transitions were discovered by Berezinskii
 -Kosterlitz-Thouless (BKT) in the 70's. They describe intriguing phase tra
 nsitions for classical statistical physics models such as\n\n - the 2d XY 
 model (spins on Z^2 with values in the unit circle)\n\n - the 2d Coulomb g
 as\n\n - the integer-valued Gaussian Free Field (or Z-ferromagnet)\n\n - A
 belian lattice gauge theory on Z^4\n\nIn this talk\, I will explain a new 
 technique to obtain quantitative lower bounds on the fluctuations induced 
 by the topological defects (vortices) on such systems at low temperature. 
 We will see in particular that the fluctuations generated by the vortices 
 are at least of the same order of magnitude as the ones produced by the so
 -called "spin-wave". Our approach is non-perturbative but it gives matchin
 g lower bounds with the fluctuations predicted from RG analysis. I will st
 art the talk by giving an overview of the above models. The talk is based 
 on joint works with Avelio Sepúlveda.\n
LOCATION:https://researchseminars.org/talk/PatC/26/
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