SU(2) gauge symmetry of the large-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>U</mml:mi></mml:math>limit of the Hubbard model

Abstract

We demonstrate explicitly the SU(2) gauge invariance of the large-$U$ limit of the Hubbard model, i.e., the Heisenberg model written in terms of electron operators with a constraint of one particle per site. We use this result to demonstrate the equivalence of two apparently very different mean-field theories.