Subnucleon fluctuations in coherent and incoherent ultra-peripheral AA collisions at LHC and RHIC with the Sartre event generator

Sartre~has been extensively used for describing photon-nuclei processes at the electron-ion collider (EIC) as well ultra-peripheral collisions (UPC) LHC and RHIC. Sartre is an event generator which implements dipole model DIS, models transverse geometry of target nucleus or proton in coordinate space. It uses Good-Walker mechanism simulating fluctuations contribute to incoherent cross section breaks up after interaction. With improved precision UPC measurements last years, a detailed test has become possible, Sartre's was found lacking. In these proceedings we add subnucleon show that this sufficient vast majority present measurements. We also find larger momentum transfers nucleus, probes gluon higher resolution, current complexity may not suffice. Future LHC, RHIC especially EIC potential reveal vacuum glean novel insights into self-interacting quantum field QCD.