Origin of Dark Matter

Determine the physical origin of dark matter (DM) that constitutes approximately 80% of the matter in the Universe, identifying the underlying particle or field responsible for this component of cosmic matter.

Background

In the section on spin, dark matter, and gravitational waves, the authors explicitly note that the origin of dark matter is not yet understood, despite strong astrophysical evidence for its existence and its dominance in the matter content of the Universe. This frames a central unresolved problem at the intersection of particle physics, cosmology, and astrophysics.

Within the same discussion, the authors outline spin-based considerations and detection strategies relevant to ultralight dark matter, including arguments that low-mass dark matter candidates (below a few eV) should be bosonic and the role of spin-based sensors in ongoing searches. These points emphasize why this open problem is highlighted in a paper about spin: the spin properties of potential dark matter candidates are directly connected to both theoretical constraints and experimental detection approaches.