Effective action for strongly correlated electron systems

TL;DR

This paper derives an effective action for the t-J model of strongly correlated electrons using su(2|1) coherent-state path integrals, highlighting an essential local constraint absent in previous phenomenological models.

Contribution

It introduces a new effective action incorporating the local no-double-occupancy constraint, crucial for accurately describing strongly correlated electron systems.

Findings

The effective action includes an important extra factor representing local constraints.

This factor reflects the phase-space rearrangement due to strong correlations.

The derived action differs significantly from earlier phenomenological models.

Abstract

The su(2|1) coherent-state path-integral representation of the partition function of the t - J model of strongly correlated electrons is derived at finite doping. The emergent effective action is compared to the one proposed earlier on phenomenological grounds by Shankar to describe holes in an antiferromagnet (Nucl.Phys. B330 (1990) 433). The t - J model effective action is found to have an important "extra" factor with no analogue in Shankar's action. It represents the local constraint of no double electron occupancy and reflects the rearrangement of the underlying phase-space manifold due to the presence of strong electron correlation. This important ingredient is shown to be essential to describe the physics of strongly correlated electron systems. Keywords: t - J model of strongly correlated electrons; su(2|1) coherent-state path integral