Superconductivity in the two-dimensional Hubbard model?

TL;DR

This paper investigates the possibility of superconductivity with d-wave symmetry in the two-dimensional Hubbard model using a refined variational wave function, focusing on intermediate interaction strengths and specific electron densities.

Contribution

It introduces a refined variational wave function to study the superconducting ground state in the 2D Hubbard model at intermediate U values.

Findings

Finite-size effects hinder definitive conclusions.

Superconducting ground state remains uncertain at studied parameters.

Further research needed to clarify the crossover regime.

Abstract

A refined variational wave function for the two-dimensional repulsive Hubbard model is studied numerically, with the aim of approaching the difficult crossover regime of intermediate values of U. The issue of a superconducting ground state with d-wave symmetry is investigated for an average electron density n=0.8125 and for U=8t. Due to finite-size effects a clear-cut answer to this fundamental question has not yet been reached.