Cornering MeV-GeV Axions and Dark Photons with LDMX

TL;DR

This paper explores how the LDMX experiment can detect MeV-GeV axions and dark photons, addressing a longstanding experimental gap in the sub-100 MeV mass range.

Contribution

It estimates LDMX's sensitivity to low-mass axions and dark photons, highlighting its potential to fill a critical experimental blind spot.

Findings

LDMX can potentially detect axions and dark photons in the sub-100 MeV mass range.

LDMX's tracking capabilities enable sensitivity to particles with longer lifetimes.

The experiment could significantly improve constraints on low-mass axions and dark photons.

Abstract

Axion-like particles (ALPs), the QCD axion, and dark photons in the MeV-GeV mass range are motivated by various dark matter models and the strong CP problem, and are ubiquitous in extensions of the Standard Model. A long-standing blind spot for experimental searches is the sub-100 MeV mass range, where the particle lifetime is too long to be constrained by prompt-decay collider searches yet too short to be reached by beam-dump experiments. We investigate and estimate the sensitivity of the Light Dark Matter eXperiment (LDMX) to such axions and dark photons, motivated by the clean environment in which these particles can be produced and by the near-target tracking capabilities of LDMX. With reasonable charged track and momentum reconstruction capabilities, we find that LDMX could close much of this low-mass blind spot for axions and dark photons.