New Constraints on ALP Electron and Photon Couplings from ArgoNeuT and the MiniBooNE Beam Dump

TL;DR

This paper uses data from MiniBooNE and ArgoNeuT beam dump experiments to set new constraints on axion-like particles' couplings to electrons and photons in the 10-100 MeV mass range, improving existing laboratory limits.

Contribution

It provides the first constraints on ALP-electron and ALP-photon couplings from MiniBooNE data and proposes a dedicated analysis with ArgoNeuT to enhance future sensitivity.

Findings

MiniBooNE data excludes previously unconstrained ALP parameter space in 10-100 MeV range.

Null results from MiniBooNE set new bounds on ALP couplings to electrons and photons.

Proposed ArgoNeuT analysis offers complementary sensitivity for future ALP searches.

Abstract

Beam dumps and fixed-target experiments have been very sensitive probes of such particles and other physics beyond the Standard Model (BSM) by considering the production of new states from the primary interaction in the beam dump. In a proton beam dump, there are many secondary interactions taking place in electromagnetic showers which may be additional production channels for pseudoscalar bosons or axion-like particles (ALPs). The target-less configuration of the MiniBooNE experiment, which collected data from $1.86 \times 10^{20}$ protons impinging directly on the steel beam dump, is an excellent test of sensitivity to these production channels of ALPs in the MeV mass region. Using the null observation of the MiniBooNE dump mode data, we set new constraints on ALPs coupling to electrons and photons produced through a multitude of channels and detected via both scattering and decays in the MiniBooNE detector volume. We find that the null result rules out parameter space that was previously unconstrained by laboratory probes in the 10-100 MeV mass regime for both electron and photon couplings. Lastly, we make the case for performing a dedicated analysis with 1.25$\times 10^{20}$ POT of data collected by the ArgoNeuT experiment, which we show to have complementary sensitivity and set the stage for future searches.