Matter vs. antimatter: we're starting to solve the mystery

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Mar 6, 2017

If it was up to theoretical physics, we wouldn't exist. Nothing would exist. This is because matter and antimatter are supposed to cancel each other out -- supposed to being the operative term here. Now physicists at the Large Hadron Collider or LHC (which smashes atoms for science) are getting slightly closer to figuring out why the stuff that makes us up doesn't automatically self-destruct.

Matter is the mirror image of antimatter, and vice versa. Charge-parity (CP) symmetry is the concept that dictates they should reflect each other in every aspect and even look the same. The only difference is that the charges of antimatter particles are the opposite of those in matter and spin in the opposite direction, so if protons and anti-protons or electrons and anti-electrons confront each other, they will automatically annihilate in a burst of photons. Matter and antimatter are supposed to be treated equally by the universe and are thought to have been produced in the same amounts during the Big Bang, at least if you go by CP symmetry. So why does anything exist at all?

Us being here means that the assumed symmetry between matter and antimatter was somehow violated for an excess of matter to escape annihilation. The problem for scientists is figuring out exactly what this violation is. No hard evidence has ever been confirmed — it's just thought that everything we know would be a gaping matterless void if something didn't defy CP symmetry. Some scientists theorize that we could possibly explain the mystery if we found out that some aspect of antimatter is the antithesis of its counterpart in matter, and while there have been slight differences observed in the decay of subatomic particles such as kaons and mesons, it isn't enough proof.

The research team at the Large Hadron Collider focused specifically on lambda-b baryons. Baryons make up protons and neutrons, and their process of decay is pushing scientists just that much closer to understanding why what was supposed to be nothing is now everything. Lambda-b baryons break down into a proton and a pair of one of two types of charged particles — either pi mesons (pions) or k mesons (kaons). Particle decay results in the sub-particles being flung off at specific angles. While both the lambdas and anti-lambdas decomposed in the same manner, where they deviated from each other was the angle at which they threw their mesons.

Marcin Kucharczyk, an associate professor at the Institute of Nuclear Physics of the Polish Academy of Sciences and collaborator on the LHC experiment, is cautiously optimistic. "Now we have something for baryons," he stated in an exclusive interview with Live Science. "When you'd observed mesons, it was not obvious that for baryons it was the same … [but] it cannot explain the asymmetry fully."

Even though it was a significant step forward, the study can't count as an actual breakthrough. More studies and statistics will be needed in order to flesh out what findings already exist. Physicists measure statistical significance, or the possibility that results could randomly happen, on a sigma, or standard deviation, scale. The LHC data received a 3.3 sigma. This indicates that there is a 1 in 4,200 chance the baryons' behavior occurred by accident, which is enough to theorize on but doesn't quite measure up to a 5 sigma, which means a 1 in 3.5 million chance.

Meanwhile, we're still here ... so scientists continue to suspect something is going on.

(via Live Science)