Axion-induced pair production: a new strategy for axion detection

TL;DR

This paper explores axion-induced pair production in nuclear electric fields as a promising method for detecting high-energy axions from sources like supernovae and the Sun, updating previous models and analyzing detection prospects.

Contribution

It introduces a detailed analysis of axion-induced pair production as a detection channel, emphasizing its effectiveness for high-energy axions and applying it to current and future detectors.

Findings

Pair production is a highly effective detection channel for high-energy axions.

Current bounds from Borexino are recast for this detection mechanism.

Detection capabilities of JUNO and Hyper-Kamiokande are evaluated.

Abstract

We revisit and update the axion-induced pair production process in a nuclear electric field mediated by the axion-electron coupling, $a+{{}^{A}_{Z}X} \rightarrow {{}^{A}_{Z}X} + e^{+} + e^{-}$. This process emerges as one of the most efficient channels for detecting axions with energies above a few MeV in large underground detectors. It is particularly relevant for detecting axions produced in nuclear reactions, such as the $p+d~\rightarrow~{ }^3 \mathrm{He}~+~a(5.5\,\mathrm{MeV})$ reaction in the solar pp-chain, and for axions originating in supernovae. Despite recent interest in detecting high-energy axions, the pair production process has received limited attention, even in scenarios where it is the dominant detection channel. This study fills this gap by demonstrating that pair production is a highly effective detection mechanism for high-energy axions. We apply our results to axions from supernovae and the solar 5.5 MeV line, recasting the current bounds of Borexino and comparing the detection capabilities of the JUNO and Hyper-Kamiokande detectors.