Pure Gravitational Dark Matter, Its Mass and Signatures

TL;DR

This paper explores a gravitational dark matter model where DM interacts only via gravity, examining its stability, production, decay signatures, and potential observational signals in cosmic rays and CMB experiments.

Contribution

It introduces a gravitational-only dark matter scenario, analyzing its stability, production mechanisms, decay channels, and observational signatures within an effective field theory framework.

Findings

DM can be stable at tree level without symmetry protection

DM mass range is approximately TeV to 10^11 GeV for correct relic abundance

Decays mainly produce gravitons, detectable via CMB and cosmic ray observations

Abstract

In this study, we investigate a scenario that dark matter (DM) has only gravitational interaction. In the framework of effective field theory of gravity, we find that DM is still stable at tree level even if there is no symmetry to protect its longevity, but could decay into standard model particles due to gravitational loop corrections. The radiative corrections can lead to both higher- and lower-dimensional effective operators. We also first explore how DM can be produced in the early universe. Through gravitational interaction at high temperature, DM is then found to have mass around TeV $\lesssim m_X \lesssim 10^{11}$GeV to get the right relic abundance. When DM decays, it mostly decays into gravitons, which could be tested by current and future CMB experiments. We also estimate the resulting fluxes for cosmic rays, gamma-ray and neutrino.