Dark Matter Dilution Mechanism through the Lens of Large-Scale Structure

Area of Science:

• Cosmology
• Particle Physics
• Astrophysics

Background:

• Entropy production is crucial for thermal relic abundance and dark matter origin models.
• A long-lived 'dilutor' particle decaying into known particles is proposed to manage relic overpopulation.

Purpose of the Study:

• To investigate the impact of a dilutor's partial decay into dark matter on the primordial matter power spectrum.
• To establish a novel method for testing dark matter dilution mechanisms using observational data.

Main Methods:

• Utilizing large scale structure observations from the Sloan Digital Sky Survey.
• Deriving stringent limits on the dilutor's branching ratio to dark matter.

Main Results:

• A stringent limit on the branching ratio of the dilutor to dark matter was derived for the first time.
• The derived limit was applied to the left-right symmetric model.
• A significant portion of the parameter space for right-handed neutrino warm dark matter was excluded.

Conclusions:

• The study provides a novel observational tool for testing dark matter dilution models.
• The findings place strong constraints on specific particle physics models, particularly those involving right-handed neutrino warm dark matter.