First Search for Dark-Trident Processes Using the MicroBooNE Detector.

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• Dark matter (DM) constitutes a significant portion of the universe's mass but remains undetected.
• The dark trident process offers a potential mechanism for producing dark matter particles from standard model interactions.
• Neutrino beams provide a unique environment to probe dark matter production via mediators like the dark photon (A').

Purpose of the Study:

• To conduct the first search for dark-trident scattering in a neutrino beam.
• To constrain the parameter space of dark matter production models involving dark photons.
• To establish limits on the kinematic mixing parameter (ϵ²) and dark photon mass (M_{A'}).

Main Methods:

• Utilized a dataset of 7.2×10²⁰ protons on target from the MicroBooNE detector at Fermilab.
• Employed a convolutional neural network to identify dark matter particle interactions within a liquid-argon time projection chamber (LArTPC).
• Analyzed data for signals consistent with dark matter production via π⁰ and η meson decays mediated by a dark photon.

Main Results:

• No significant signal for dark-trident scattering was observed.
• Established 90% confidence level limits on the squared kinematic mixing parameter (ϵ²) as a function of dark photon mass (10≤M_{A^{'}}≤400 MeV).
• Constrained previously unexplored regions for fermion or scalar dark matter particle (χ) production.

Conclusions:

• The search sets new limits on dark matter models, particularly those involving dark photons as mediators.
• The results exclude a portion of the parameter space for dark matter particle masses and dark fine-structure constants (0.1≤α_{D}≤1).
• This study demonstrates the potential of LArTPCs in neutrino beams for probing fundamental physics beyond the Standard Model.