It appears that the Universe is full of dark matter—around six times more of it than there is regular matter. It has obvious visible effects, like the way it bends light from distant galaxies. Despite dedicated searches, no signs of a dark matter particle explaining these effects have turned up.
Perhaps instead physicists will be able to find some dark force, a portal into the dark world. Such a “dark photon” would be dark matter’s equivalent of a photon, a the way that dark matter particles interact with one another. Scientists are searching for such a particle. It hasn’t turned up yet, based on new results from the Large Hadron Collider in Geneva Switzerland. But the search isn’t over—and a lot of physicists are really excited about it.
“LHCb had to work really hard to get to this mass range,” Caterina Doglioni, a researcher at Lund University who was not involved in the study, told Gizmodo. “The way they did it is quite cool. They reinvented the data taking of LHC experiments”
Physicists have been using plenty of methods such as big vats of liquid xenon to try and find dark matter particles directly, and still have no leads. Dark photons would take Dark Matter’s story deeper, and imply that there’s a dark universe governed by dark forces.
“What we now about dark matter is very little. One of the pressing questions is, how does dark matter interact with itself? That’s a wide open space,” study author Mike Williams told Gizmodo. He said that discovering this particle could open up an entirely new area of study.
Actually looking for this particle is a chore. Williams hoped that the LHC’s high-energy proton collisions would result in dark photons that then decay into other particles called the muon and its antiparticle partner. But there are tons of less-ghostly ways that particles in the searched-through mass range could decay into two muons. In some cases, hunting for it is like trying to find out whether someone dumped a bag of M&Ms into a vat of M&Ms at the candy factory by comparing the contents of the vat to the factory’s usual output…..more here