Symmetric Tensor Coupling in Holographic Mean-Field Theory: Deformed Dirac Cones

TL;DR

This paper extends holographic mean-field theory to include symmetric tensor order parameters, analyzing their effects on spectral density and light cone tilting, with implications for real materials like strained graphene.

Contribution

It introduces a generalized holographic framework incorporating symmetric tensor fields, revealing their impact on spectral features and causality preservation.

Findings

Classification of tensor effects on spectral density

Realistic modeling of type-II Dirac cones

Causality-preserving light cone tilting

Abstract

We extend the holographic mean-field theory to rank-two symmetric tensor order parameter field coupled with fermion. We classify the roles of symmetric tensor order according to the effect on the spectral density: cone-angle change, squashing, and tilting of the spectral light cones. The over-tilted light cone is also achieved in a generalized prescription, which consistently preserves the causality condition. Our results provide agreements between the holographic spectra with those observed in real materials, such as type-II Dirac cones and strained graphene.