Discovering Dark Matter at the LHC through Its Nuclear Scattering in Far-Forward Emulsion and Liquid Argon Detectors

TL;DR

This paper explores the potential of future far-forward detectors at the LHC to detect dark matter produced in proton collisions, focusing on nuclear scattering methods to probe new parameter space for light dark matter particles.

Contribution

It introduces the use of FASERν2 and FLArE detectors for dark matter detection via nuclear scattering, expanding the search capabilities in the MeV to GeV mass range.

Findings

Dark matter detection prospects in the 5 MeV to 500 MeV mass range.

Effective background suppression techniques for neutrino-induced events.

Potential to discover dark matter in cosmologically-favored parameter space.

Abstract

The LHC may produce light, weakly-interacting particles that decay to dark matter, creating an intense and highly collimated beam of dark matter particles in the far-forward direction. We investigate the prospects for detecting this dark matter in two far-forward detectors proposed for a future Forward Physics Facility: FASER$\nu$2, a 10-tonne emulsion detector, and FLArE, a 10- to 100-tonne LArTPC. We focus here on nuclear scattering, including elastic scattering, resonant pion production, and deep inelastic scattering, and devise cuts that efficiently remove the neutrino-induced background. In the invisibly-decaying dark photon scenario, DM-nuclear scattering probes new parameter space for dark matter masses 5 MeV $\lesssim m_{\chi} \lesssim$ 500 MeV. When combined with the DM-electron scattering studied previously, FASER$\nu$2 and FLArE will be able to discover dark matter in a large swath of the cosmologically-favored parameter space with MeV $\lesssim m_{\chi} \lesssim $ GeV.