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SUMMARY:The critical behavior of $\\phi^4_4$ - Martin Lohmann (University 
 of British Columbia)
DTSTART:20181023T140000Z
DTEND:20181023T150000Z
UID:TALK112798@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:We discuss the approach to the critical point of the $phi^4$ m
 odel in 4 dimensions. One of the major successes of the renormalization gr
 oup technique has been to explain why this model features logarithmic corr
 ections to the scaling predictions for the blow up of thermodynamic quanti
 ties. We review the strategy of the proof in the "symmetric regime" with z
 ero external magnetic field\, in which case this is a classic result. We t
 hen present the proof of logarithmic corrections to the magnetization as t
 he magnetic field tends to zero. Despite being a central aspect of the mod
 el\, these have been an open problem until now\, probably because technica
 l complications where expected due to the broken symmetry. We have found t
 hese concerns to be unfounded\, and our proof only needs a single cluster 
 expansion on top of the classic RG construction for the critical point.
LOCATION:Seminar Room 1\, Newton Institute
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