Dec 8, 2010 14:54 GMT  ·  By
This is what rowing your boat inside a particle accelerator built to find neutrinos and decaying protons looks like
   This is what rowing your boat inside a particle accelerator built to find neutrinos and decaying protons looks like

A team of Canadian investigators at the University of British Columbia (UBC) propose the existence of a new particle, dubbed particle X, that could explain dark matter, antimatter, and also why there is enough normal matter in the Universe for us to exist, all in one fell swoop.

Details of the particle can be found in the November 19 issue of the top scientific journal Physical Review Letters. The paper was coauthored by UBC physicist Kris Sigurdson.

One of the most important things about the new work is that it manages to explain why we exist. According to the basic laws of physics, there shouldn't be so much normal matter in the Universe.

When the Universe exploded the Cosmos into being, it theoretically produced equal amounts of matter and antimatter, and the two should have annihilated each other completely and immediately.

Obviously, that did not happen, as evidenced by the fact that we are here, as well as by all the galaxies, clusters, stars and planets in the known Universe and beyond.

The proposed particle X could also help clear the mystery related to the composition of dark matter, the stuff that accounts for most of the cosmic mass, but which does not interact with normal matter. Its effects can only be seen through the gravitational pull it exerts on galaxies.

“We know you have to have these two ingredients to the universe, both atoms and dark matte. Since you know you need those ingredients anyway, it seems like a natural thing to try to explain them from the same mechanism,” says Sigurdson, quoted by Wired.

“If matter and antimatter were created in equal amounts in the early Universe, they would all have annihilated [each other]. There has to be some asymmetry that was left over,” adds Sean Tulin.

The expert holds an appointment as a theoretical physicist at the Canadian physics institute TRIUMF. “If our theory is right, it would tell you what dark matter is,” he adds.

The new study was conducted by Tulin and Sigurdson, in collaboration with Brookhaven National Lab (BNL) physicist Hooman Davoudiasl and TRIUMF expert David Morrissey.

The basic thought flow of the study is fairly simple: the cosmic asymmetry can be explained only if we consider that some antimatter is missing. Given that we can't see dark matter, it may be that this is the form the missing antimatter has taken after losing the “battle” with normal matter.

According to Tulin, the hypothesized particle X has nothing to do with weakly interacting massive particle (WIMP), the basic building blocks experts not believe dark matter is made up of.

The team says that X has a separate antiparticle, creatively called anti-X. At the Big Bang, equal amounts of these particles were produced, but they soon started to decay.

Each X decayed into a neutron or two dark-matter particles (Y and Φ), while each anti-X decayed into an anti-neutron or some anti-dark matter.

But the X exhibited a preference for decaying into regular matter, and therefore produced more neutrons. At the same time, anti-X preferred to decay into more anti-dark matter than anti-neutrons.

As collisions and annihilations began between the complementary particles, only extra amounts of neutrons and anti-dark matter particles endured.

“The protons and neutrons can’t annihilate completely with their antiparticles, because there’s not enough to annihilate with. The same story happens in the hidden sector as well,” Tulin explains.

“Some dark matter can’t annihilate with anything. So you’re left with some extra dark matter in the Universe,” he adds. This may help explain the large concentration of the stuff in the Cosmos.

“This is only the beginning. There’s other puzzles out there in particle physics, and we’d like to connect as many of those as possible,” Sigurdson concludes.