Axionlike particles searches in reactor experiments

TL;DR

Reactor experiments can effectively search for axionlike particles (ALPs) with masses below 10 MeV by utilizing their intense photon flux, offering a complementary approach to astrophysical observations and probing new parameter regions.

Contribution

This paper demonstrates the potential of reactor neutrino experiments to explore previously untested ALP parameter space, especially in the MeV mass range and for specific couplings.

Findings

Reactor experiments can test ALP-photon couplings and masses beyond current astrophysical limits.

They can explore ALP-electron couplings around 10^{-8}.

They can probe ALP-nucleon couplings near 10^{-9}.

Abstract

Reactor neutrino experiments provide a rich environment for the study of axionlike particles (ALPs). Using the intense photon flux produced in the nuclear reactor core, these experiments have the potential to probe ALPs with masses below 10 MeV. We explore the feasibility of these searches by considering ALPs produced through Primakoff and Compton-like processes as well as nuclear transitions. These particles can subsequently interact with the material of a nearby detector via inverse Primakoff and inverse Compton-like scatterings, via axio-electric absorption, or they can decay into photon or electron-positron pairs. We demonstrate that reactor-based neutrino experiments have a high potential to test ALP-photon couplings and masses, currently probed only by cosmological and astrophysical observations, thus providing complementary laboratory-based searches. We furthermore show how reactor facilities will be able to test previously unexplored regions in the $\sim$MeV ALP mass range and ALP-electron couplings of the order of $g_{aee} \sim 10^{-8}$ as well as ALP-nucleon couplings of the order of $g_{ann}^{(1)} \sim 10^{-9}$, testing regions beyond TEXONO and Borexino limits.