Constraint Quantization of Slave-Particle Theories

Abstract

We start from the Barnes-Coleman slave-particle description, where the Hubbard operators $X$ are decomposed into a product of fermionic ($f_α$) and bosonic ($b$) operators. The quantum mechanical constraint $b^{\dagger} b + \sum_α f_α^{\dagger} f_α = 1$ is treated within the framework of Dirac's method for the quantization of classical constrained systems. This leads to modified algebraic properties of the fundamental operators: $b b^{\dagger} b = b$, $f_α f_β^{\dagger} f_γ = δ_{αβ} f_γ$ and $ f_α b^{\dagger}= 0 $. Thereby the algebra of the $X$-operators is preserved exactly on the operator level. Matrix representations of the above algebra are constructed and a resolvent-like perturbation theory for the single-impurity Anderson model is developed.