![]() If physicists at SuperKamiokande went back through their data and looked at slightly different energies, they may be able to find traces of dark matter. An enormous underground tank of water in Japan, called SuperKamiokande, was designed to look for the decaying protons, but has so far found nothing. ![]() Proton decay isn't allowed by the standard model of particle physics, but some theories that go beyond the standard model allow it. A dark-matter particle can sometimes smack into a proton or a neutron and destroy it, creating a signature similar to a proton decaying. In this model, dark matter doesn't interact with regular matter very often - but it can happen. The signatures of this new form of dark matter could be detected by existing experiments. He compares the balance to a yin-yang: "You end up with a little bit more matter and a little bit more antimatter, but they're in exact compensation with each other." "That's why the light stuff, the visible matter that we all know and love and are used to, is in exact balance with the excess in the dark matter," Sigurdson said. If the dark-matter particles each have a mass between two and three times the proton's mass, then the universe ends up with five times more dark matter than regular matter. So you're left with some extra dark matter in the universe."īut in the new model, there should be the same absolute number of regular-matter particles and dark-matter particles left after all the particles that can destroy each other are gone. Some dark matter can't annihilate with anything. "The same story happens in the hidden sector as well. "The protons and neutrons can't annihilate completely with their antiparticles, because there's not enough to annihilate with," Tulin said. Anti-X preferred decaying into anti-dark matter, and so produced more of it.Īfter all the particles and anti-particles that could find each other collided and eliminated each other, the universe was left with some extra neutrons and a corresponding number of extra anti-dark matter particles. Every anti-X converted to an anti-neutron or some anti-dark matter.īut the hypothetical X particle would rather decay into ordinary matter than dark matter, so it produced more neutrons than dark matter. Each X decayed into either a neutron or two dark-matter particles, called Y and Φ. The proposed particle, named simply "X," has a separate antiparticle called "anti-X." Equal amounts of X and anti-X were created in the Big Bang, and then decayed to lighter particles. ![]() The new theoretical particle "is completely different from the WIMP idea," Tulin said. Based on current theories, WIMPs are expected to be about 100 times as massive as a proton, and to be their own antiparticle - whenever two WIMPs meet up in space, they annihilate each other. ![]() ![]() The most popular candidate for dark matter is a theoretical weakly interacting massive particle, or WIMP, that connects only with the weak nuclear force and gravity, making it undetectable by eyes, radios and telescopes at all wavelengths. Most of what we know about dark matter is that it is mysterious stuff that makes up a quarter of the energy density of the universe, but refuses to interact with regular matter except through gravity. ![]()
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