The existence of dark matter can be traced back to the pioneering discoveries of Fritz Zwicky and Jan Oort that the motion of galaxies in the Coma cluster, and of nearby stars in our own Galaxy, do not follow the expected motion based on Newton's law of gravity and the observed visible masses. Since then a host of experimental data from precise measurements of the cosmic microwave background, of gravitational lensing of galaxy clusters, and of the rotational speeds of stars and galaxies, provide strong, internally consistent, evidence for the existence of dark matter as a particle. But we still do not have any direct evidence for dark matter, let alone have some idea as to its physical properties or its non-gravitational interactions with the Standard Model particles.
The theory effort at Los Alamos is focused on pursing a number of questions related to the physics of dark matter.
What is the dark matter particle? How do we experimentally measure its physical properties?
- What is the phase space distribution of astrophysical dark matter?
- How large are the long-distance QCD corrections to direct dark matter - nucleus scattering?
- Can dark matter - neutrino interactions be important?
- What are the implications of searches for new physics at the LHC on the physical properties of dark matter?
- What is its large scale structure and evolution of the Universe?