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

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 $G_{aγγ'}$.

Figures (11)

• Figure 1: Feynman diagrams for the process $\gamma e^-\to\gamma' ae^-$ with the dark axion portal $G_{a\gamma\gamma'}$.
• Figure 2: The cross section of $\gamma e \to e \gamma' a$ intergrating over the energy of photons from reactors with $G_{a\gamma\gamma'}=1\,{\rm GeV^{-1}}$.
• Figure 3: The normalized energy spectra for ALP (left) and dark photon (right) produced through $\gamma e^-\to e^- \gamma' a$ process from reactor for different choices of the masses.
• Figure 4: The event spectrum from ALP (left) and dark photon (right) decay for detectors located at 11 m (solid lines) and 22 m (dashed lines) from the reactor with $G_{a\gamma\gamma'}=10^{-2}\,\rm GeV^{-1}$.
• Figure 5: The event rate per year from dark photon (left panel) and ALP (right panel) decays as function of the coupling $G_{a\gamma\gamma'}$ for several difference benchmarks of dark photon and ALP masses.