Sensitivity of the RECODE Reactor CEvNS Experiment to the Dark Axion Portal

TL;DR

This paper explores how reactor CEvNS experiments, especially RECODE, can detect or constrain the dark axion portal, offering improved sensitivity over existing collider bounds in the sub-MeV energy range.

Contribution

It demonstrates the potential of reactor CEvNS experiments to probe the dark axion portal coupling, providing new constraints and highlighting their advantages over collider experiments.

Findings

Reactor CEvNS experiments can probe the dark axion portal coupling down to ~10^{-3}.

Enhanced sensitivity in the sub-MeV energy region compared to B factory constraints.

RECODE and similar experiments can significantly improve BSM searches for axion-like particles.

Abstract

Reactor CEvNS experiments provide a powerful probe of the physics beyond the Standard Model (BSM) with the intense flux of neutrinos, photons, and other particles produced in nuclear reactors. In this work, we investigate the sensitivity of reactor CEvNS experiments to the dark axion portal, which connects the axion or axion-like particle to the dark photon. We focus in particular on the RECODE experiment, while also considering other reactor-based experiments such as CONUS and MINER. We find that reactor CEvNS experiments offer enhanced sensitivity in the sub-MeV region compared with the existing constraints from B factories, and can probe the portal coupling down to $\mathcal{O}(10^{-3})$ for $G_{a\gamma\gamma'}$.