Probing Benchmark Models of Hidden-Sector Dark Matter with DAMIC-M

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• The nature of dark matter (DM) remains one of the most significant unsolved problems in physics.
• Sub-GeV dark matter interacting with electrons is a theoretically motivated candidate.
• Detecting such low-mass DM requires highly sensitive experiments with low background noise.

Purpose of the Study:

• To search for sub-gigaelectronvolt (GeV) dark matter particles that interact with electrons.
• To improve upon previous searches by utilizing a significantly lower detector background rate and larger data exposure.
• To constrain the properties of dark matter particles, particularly their mass and mediator type.

Main Methods:

• Utilized the DAMIC-M prototype detector, employing skipper charge-coupled devices (CCDs).
• Searched for dark matter interactions by identifying groups of two or three adjacent pixels with a specific low charge (2-4 electrons).
• Accumulated a large data exposure of approximately 1.3 kg-day with a substantially reduced single electron rate.

Main Results:

• Observed 144 candidate events with 2 electrons and 1 candidate with 4 electrons.
• The expected background from known sources was calculated to be 141.5 and 0.071 events, respectively.
• No statistically significant excess above the expected background was found, indicating no evidence for a dark matter signal.

Conclusions:

• Placed stringent constraints on dark matter particles with masses between 1 and 1000 MeV/c^2 interacting with electrons.
• Excluded theoretically motivated benchmark scenarios for dark matter production mechanisms (freeze-in and freeze-out) for a wide range of dark matter masses below 1 GeV/c^2.
• The results highlight the sensitivity of DAMIC-M for exploring low-mass dark matter candidates.