Coming up with and then finding new particles is very much the quest of dark matter researchers. The “coming up with” particles park is easy – math makes it possible to define all sorts of things. It’s the finding of the particles that is hard.
But things that are hard, aren’t impossible.
Everything in the universe is made up of particles and energy. Regular matter is made of fundamental particles like electrons, and composite particles like protons that are made up of combinations of 3 quarks. As far as we know, all stable composite particles – leptons – are made of 3 and only 3 quarks. But quarks don’t have to come together in groups of 3, and we don’t necessarily know about everything that is out there.
Using massive particle colliders, we have been able to slam together bits of regular matter with so much force that it turns into almost pure energy that re condenses into myriad stable and unstable particles. In these flashes of unstable particles configurations of 4 and 5 quarks have been discovered. It is now theorized that 6-quarks may be able to come together to form stable particles. Called hexaquarks, these undiscovered particles are being actively sought as a dark matter candidate. Researcher Glennys Farrar at NYU has theorized that these particles may be trapped inside various elements in the crust of the earth, such as oxygen-18. Folks are literally weighing different oxygen-18 atoms to see if they can measure the excess weight hexaquarks might cause. Folks are also looking through results from past particle collisions at the world’s various accelerators, and there are hints of a large particle in data from Germany’s WASA experiment at the COSY particle accelerator. It looks like there might be a 2.4 billion electron volt particle in the data, and this is consistent with a 6 quark particle. It isn’t conclusive, but it’s a hint, and this is the best we’ve got right now.
Other researchers are also looking for flickers in neutrino detectors that aren’t caused by neutrinos and could be dark matter, and others are simply brainstorming new possibilities.
But no one can really say exactly what dark matter is. The best we’ve got, based on observations, is dark matter is a particle that is a pain in the expletive to find.