Reply to Robinson and Michaud, arXiv:2002.08893

TL;DR

This paper is a formal reply to a comment on a previous work discussing excesses in low-threshold dark matter searches, emphasizing the need for direct calibration of plasmon charge yields at low energies.

Contribution

It clarifies and defends the original claims about plasmon behavior at low energies, addressing objections and emphasizing calibration needs.

Findings

Plasmon charge yields at ~10 eV are critical for dark matter detection.

Objections about plasmon-phonon branching do not invalidate original conclusions.

Future measurements are essential for calibration at low energy scales.

Abstract

We respond to Robinson and Michaud's (RM) comment (arXiv:2002.08893) on our recent preprint arXiv:2002.06937, in which we discuss recent excesses in low-threshold dark matter searches, and offer a potential unifying dark matter interpretation. We thank RM for their feedback, which highlights the critical need for future measurements to directly calibrate plasmon charge yields for low $\sim$ 10 eV energy depositions. RM objected to our assertion that plasmons generated at energy scales below 100~eV may have a large branching fraction into phonons. As we argue below, the points raised by RM do not invalidate our primary conclusions, as they pertain to a much different energy scale than we discuss in our paper.