Search for the Neutron Decay n→X+γ, Where X is a Dark Matter Particle

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• Discrepancies exist between neutron lifetime measurements from beam and bottle methods.
• A proposed dark matter decay mode (n→X+γ) may explain these discrepancies.

Purpose of the Study:

• To search for the hypothesized dark matter decay mode (n→X+γ).
• To determine if this decay mode can account for the neutron lifetime puzzle.

Main Methods:

• Utilized a Compton-suppressed high-purity germanium detector.
• Searched for monoenergetic gamma rays from neutron decay within a coated stainless-steel bottle.
• Employed Monte Carlo simulations and radioactive source calibrations for efficiency determination.

Main Results:

• No evidence was found for the proposed dark matter decay mode.
• The possibility of a decay branch strong enough to explain the lifetime discrepancy was excluded.
• The exclusion was made with 97% confidence.

Conclusions:

• The dark matter decay mode (n→X+γ) is not the explanation for the neutron lifetime discrepancy.
• This study places constraints on new physics beyond the Standard Model.