Role of symmetry and dimension on pseudogap phenomena

TL;DR

This paper investigates how symmetry and dimensionality influence pseudogap phenomena in the attractive Hubbard model using Monte Carlo simulations, revealing conditions under which pseudogaps form and their relation to symmetry properties.

Contribution

It demonstrates the emergence of pseudogaps in the 2D attractive Hubbard model and explores how symmetry, especially SO(n), affects the pseudogap temperature relative to the critical temperature.

Findings

Pseudogap appears at a crossover temperature $T_X$ with precursors of Bogoliubov quasiparticles.

The pseudogap occurs in the renormalized classical regime when the correlation length exceeds a thermal de Broglie wavelength.

Near SO(n) symmetric points with n>2, the ratio $T_X/T_c$ can become arbitrarily large.

Abstract

The attractive Hubbard model in d=2 is studied through Monte Carlo simulations at intermediate coupling. There is a crossover temperature $T_X$ where a pseudogap appears with concomitant precursors of Bogoliubov quasiparticles that are not local pairs. The pseudogap in $A(k,\omega)$ occurs in the renormalized classical regime when the correlation length is larger than the direction-dependent thermal de Broglie wave length, $\xi_{th}=\hbar v_{F}(k)/k_{B}T.$ The ratio $T_{X}/T_{c}$ for the pseudogap may be made arbitrarily large when the system is close to a point where the order parameter has SO(n) symmetry with n>2. This is relevant in the context of SO(5) theories of high $T_c$ but has more general applicability.