Massive Gravitons as Feebly Interacting Dark Matter Candidates

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• The nature of dark matter remains one of the most significant unsolved problems in physics.
• The freeze-in mechanism provides a viable production pathway for dark matter particles.
• Gravitons, as mediators of gravity, are theoretically predicted but experimentally elusive.

Purpose of the Study:

• To investigate the potential of massive spin-2 gravitons as dark matter candidates.
• To explore the implications of chiral enhancement on graviton production cross sections.
• To determine the viable mass range and parameter space for graviton dark matter within specific theoretical models.

Main Methods:

• Detailed calculations of production cross sections for massive spin-2 gravitons.
• Analysis of chiral enhancement effects on these cross sections.
• Application of a novel calculation to a Randall-Sundrum model with multiple branes.

Main Results:

• A significant chiral enhancement in the production cross sections of massive spin-2 gravitons was discovered.
• This enhancement makes these gravitons ideal dark matter candidates for the freeze-in mechanism.
• The results indicate graviton dark matter masses in the keV-MeV range, consistent with small-scale structure observations.
• A significant parameter space within the Randall-Sundrum model allows the first two massive gravitons to saturate the dark matter relic density.

Conclusions:

• Massive spin-2 gravitons are compelling sub-MeV dark matter candidates.
• The freeze-in mechanism, coupled with chiral enhancement, provides a robust production route.
• The Randall-Sundrum model offers a concrete framework supporting these findings.