Excitation spectrum and critical exponents of a one-dimensional integrable model of fermions with correlated hopping

TL;DR

This paper analyzes the excitation spectrum of an integrable one-dimensional fermion model with correlated hopping, revealing the nature of gapless and gapped excitations, and how correlations evolve with particle density.

Contribution

It provides a detailed analysis of the excitation spectrum and correlation functions of a solvable fermion model, highlighting the dominance of multiplet correlations at high density.

Findings

Gapless particle-hole excitations characterized

Presence of gapped spin-wave like excitations

Dominance of multiplet correlations at high density

Abstract

We investigate the excitation spectrum of a model of $N$ colour fermions with correlated hopping which can be solved by a nested Bethe ansatz. The gapless excitations of particle-hole type are calculated as well as the spin-wave like excitations which have a gap. Using general predictions of conformal field theory the long distance behaviour of some groundstate correlation functions are derived from a finite-size analysis of the gapless excitations. From the algebraic decay we show that for increasing particle density the correlation of so-called $N$-multiplets of particles dominates over the density-density correlation. This indicates the presence of bound complexes of these $N$-multiplets. This picture is also supported by the calculation of the effective mass of charge carriers.