The fate of 1D spin-charge separation away from Fermi points

TL;DR

This paper develops a non-perturbative theory for the dynamic response of 1D spin-1/2 fermions at arbitrary momenta, revealing that spin-charge separation and singularities persist beyond Fermi points.

Contribution

It introduces a zero-temperature, non-perturbative framework using mobile impurity Hamiltonians to analyze threshold singularities away from Fermi points.

Findings

Spin-charge separation persists at arbitrary momenta.

Threshold singularities follow power-law behavior.

Exponents are expressed via the spinon spectrum.

Abstract

We consider the dynamic response functions of interacting one dimensional spin-1/2 fermions at arbitrary momenta. We build a non-perturbative zero-temperature theory of the threshold singularities using mobile impurity Hamiltonians. The interaction induced low-energy spin-charge separation and power-law threshold singularities survive away from Fermi points. We express the threshold exponents in terms of the spinon spectrum.