# Plasmons in Holographic Graphene

### Submission summary

 As Contributors: Ulf Gran · Marcus Tornsö · Tobias Zingg Arxiv Link: https://arxiv.org/abs/1804.02284v5 (pdf) Date accepted: 2020-06-11 Date submitted: 2020-05-27 Submitted by: Gran, Ulf Submitted to: SciPost Physics Discipline: Physics Subject area: High-Energy Physics - Theory Approaches: Theoretical, Computational

### Abstract

We demonstrate how self-sourced collective modes - of which the plasmon is a prominent example due to its relevance in modern technological applications - are identified in strongly correlated systems described by holographic Maxwell theories. The characteristic $\omega \propto \sqrt{k}$ plasmon dispersion for 2D materials, such as graphene, naturally emerges from this formalism. We also demonstrate this by constructing the first holographic model containing this feature. This provides new insight into modeling such systems from a holographic point of view, bottom-up and top-down alike. Beyond that, this method provides a general framework to compute the dynamical charge response of strange metals, which has recently become experimentally accessible due to the novel technique of momentum-resolved electron energy-loss spectroscopy (M-EELS). This framework therefore opens up the exciting possibility of testing holographic models for strange metals against actual experimental data.

### Ontology / Topics

See full Ontology or Topics database.

Published as SciPost Phys. 8, 093 (2020)

We thank the referee for his/her positive comments regarding the question addressed in the paper and for the constructive criticism.

To address the lack of clarity regarding technical details, we have extended appendix A by adding technical details regarding how we perform the linear response analysis, and in the new appendix B we have listed the equations of motion for the perturbations that we solve. We considered this linear response analysis to be part of the standard lore, but adding the details clearly makes the paper more self-contained.

We have also added a discussion regarding holographic renormalization in the beginning of appendix A, where the action is introduced, and added the two standard counterterms explicitly in the action (they were of course used in the previous computations). Note that no counterterm is necessary for the Maxwell part of the action.

We hope that after these additions, addressing the concerns of the referee, the paper will be judged ready for publication.

### List of changes

Appendix A: Extended to include technical details regarding how we perform the linear response analysis.
Appendix A: Discussion regarding holographic renormalisation added after eq (24), where the action is introduced, and the two standard counterterms have been written out explicitly in the action.
New appendix B added containing all the equations of motion for the perturbations that we solve.

### Submission & Refereeing History

Resubmission 1804.02284v5 on 27 May 2020
Submission 1804.02284v4 on 9 July 2019

## Reports on this Submission

### Report

After reading the new manuscript and the response of the authors, I am happy to recommend its publication without further delays.

• validity: good
• significance: high
• originality: good
• clarity: high
• formatting: excellent
• grammar: excellent