# Spectroscopy of spinons in Coulomb quantum spin liquids

## TL;DR

This paper investigates how emergent photons influence spinon production in Coulomb quantum spin liquids, revealing significant modifications to the threshold behavior and radiation phenomena, aligning with recent experimental findings.

## Contribution

It provides a theoretical analysis of the impact of emergent photons on spinon production thresholds and radiation in Coulomb spin liquids, a novel insight into their spectroscopic signatures.

## Key findings

- Emergent photons cause an abrupt onset in spinon production cross-section.
- Photon effects suppress finite-momentum intensity and enable Cerenkov radiation.
- Results align with recent numerical and experimental observations.

## Abstract

We calculate the effect of the emergent photon on threshold production of spinons in $U(1)$ Coulomb spin liquids such as quantum spin ice. The emergent Coulomb interaction modifies the threshold production cross-section dramatically, changing the weak turn-on expected from the density of states to an abrupt onset reflecting the basic coupling parameters. The slow photon typical in existing lattice models and materials suppresses the intensity at finite momentum and allows profuse Cerenkov radiation beyond a critical momentum. These features are broadly consistent with recent numerical and experimental results.