A world without WIMPs

There was talk over lunch and coffee of dark forces, dark photons, and dark neutrons.1 (emphasis added)

This is the extent of what is actually known about dark matter and any other entities from the dark sector of particle physics.  At a workshop where more than 100 physicists took over the University of Maryland, titled “US Cosmic Visions: New Ideas in Dark Matter,” attendees were encouraged to think more broadly to solve the vexing problem of the non-detection of dark matter particles in all experiments that have ever been tried for the last 40 years, at least.

They spoke of axions and other dark-matter candidates so lightweight that they would be detected as waves, and of particles so heavy that they would clump together and encounter Earth only occasionally as a vast invisible glob.1

Despite impressive sensitivity, dark-matter detection experiments such as Large Underground Xenon (detector array above) have not found any evidence of WIMPs. Credit: C. H. Faham/LUX

A recalibration for the dark-matter community

For decades physicists have been fixated on the putative WIMP, a Weakly Interacting Massive Particle, which allegedly has a tendency to intermittently mingle with ordinary matter via the weak force. WIMPs have been alleged to inhabit our part of the Galaxy but all experiments, like the Large Underground Xenon (LUX) detector array, have failed to find any trace of their existence.  Theorists developed ideas that WIMPs might be the lowest mass yet stable supersymmetric particle, called the neutralino but experimentalists with vast, exquisitely sensitive underground detectors such as the LUX array or using the powerful particle accelerator the Large Hadron Collider (LHC) found no such particles though they were meant to be constantly streaming stealthily through our planet. Now, Continue reading