Strong constraints on sub-GeV dark sectors from SLAC beam dump E137

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• The nature of dark matter remains one of the most significant unsolved problems in physics.
• The muon anomalous magnetic moment shows a persistent discrepancy between experimental measurements and the Standard Model prediction.
• Dark photons are hypothetical particles that could mediate interactions between the visible and dark sectors.

Purpose of the Study:

• To present new constraints on sub-GeV dark matter and dark photons.
• To investigate the potential of the E137 electron beam-dump experiment to probe dark sector physics.
• To test the hypothesis that dark photons decaying into light dark-sector particles could explain the muon anomalous magnetic moment anomaly.

Main Methods:

• Analysis of data from the E137 electron beam-dump experiment conducted at SLAC.
• Searched for a specific signature of dark matter scattering off electrons, producing electromagnetic showers.
• Constrained parameter space for dark matter and dark photon interactions based on the absence of signal.

Main Results:

• Established new and significant constraints on sub-GeV dark matter and dark photons.
• Constrained parameter space relevant to explaining the muon anomalous magnetic moment discrepancy.
• Showed that dark photon models can be restricted in parameter space where dark matter relic density is achieved via thermal freeze-out.

Conclusions:

• The E137 experiment provides powerful constraints on dark sector models.
• The results limit the parameter space for dark photons potentially explaining the muon g-2 anomaly.
• E137 demonstrates the viability of beam-dump experiments for future searches of sub-GeV dark-sector particles.