Effective action for strongly correlated electron systems

The su(2|1)su(2|1) coherent-state path-integral representation of the partition function of the t–Jt–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 [R. Shankar, Nucl. Phys. B 330 (1990) 433]. The t–Jt–J model effective action is found to have an important “extra” factor with no analogue in Shankarʼs 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.