Klzllersü, A.Sizer, T.Pennington, M.Williams, A.Williams, R.2016-08-222016-08-222015Physical Review D: Particles, Fields, Gravitation and Cosmology, 2015; 91(6):065015-1-065015-171550-79981550-2368http://hdl.handle.net/2440/100599Published 13 March 2015We present a comprehensive numerical study of dynamical mass generation for unquenched QED in four dimensions, in the absence of four-fermion interactions, using the Dyson-Schwinger approach. We begin with an overview of previous investigations of criticality in the quenched approximation. To this we add an analysis using a new fermion-antifermion-boson interaction ansatz, the Kızılersü-Pennington (KP) vertex, developed for an unquenched treatment. After surveying criticality in previous unquenched studies, we investigate the performance of the KP vertex in dynamical mass generation using a renormalized fully unquenched system of equations. This we compare with the results for two hybrid vertices incorporating the Curtis-Pennington vertex in the fermion equation. We conclude that the KP vertex is as yet incomplete, and its relative gauge variance is due to its lack of massive transverse components in its design.en© 2015 American Physical SocietyJournal article003002756310.1103/PhysRevD.91.0650150003514332000102-s2.0-84927581935119007Williams, A. [0000-0002-1472-1592]