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SUMMARY:[NT/RBRC seminar] Eikonal Expansion for Classical Gluon Fields
DTSTART:20261113T160000Z
DTEND:20261113T180000Z
DTSTAMP:20261113T185700Z
UID:indico-event-34532@indico.bnl.gov
DESCRIPTION:Speakers: Alexander DeBrizzi (University of Connecticut)\n\nTh
 e eikonal approximation is both a ubiquitous and natural approximation in 
 high-energy physics. This approximation is applied\, for example\, in the 
 McLerran-Venugopalan (MV) model and Color-Glass-Condensate (CGC) framework
 \, which underlie many low-$x$ physics developments. The validity of this 
 approximation requires that subeikonal terms are higher-order corrections 
 to the leading eikonal behavior\, and this has been assumed wherever the a
 pproximation has been applied. However\, in this talk\, we show that this 
 is not correct and that a naive\, complete expansion in eikonality is not 
 a valid perturbative treatment for classical gauge fields. Specifically\, 
 we demonstrate that subeikonal fields make a leading contribution to the e
 quations of motion for fields at a lower order in eikonality due to diverg
 ences associated with the fields at high momentum. Nevertheless\, we find 
 that the validity of the eikonal approximation can be restored if we separ
 ate the classical gauge field into low- and high-momentum modes\, whereupo
 n the color current in the equations of motion for the eikonal moments of 
 the field are renormalized by effects of the interaction between the two m
 odes. Additionally\, we see that even for strong fields\, in the framework
  of low-$x$ physics\, the equation for the leading eikonal behavior is lin
 ear. We conclude that we can preserve the eikonal approximation\, so as lo
 ng as we understand correctly what in fact the color current in this appro
 ximation represents. preprint: arXiv:2608.22536\n\nhttps://indico.bnl.gov/
 event/34532/
LOCATION:CFNS library (https://bnl.zoomgov.com/j/1614715193?pwd=WkwxODVWdz
 Zzb29zQnZRVGp3VTBDQT09)
URL:https://indico.bnl.gov/event/34532/
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