The LHCb team stands in front of their experiment, the LHCb detecor, at the Large Hadron Collider in Geneva. Image Credit: CERN/Maximilien Brice, Rachel BarbierMatter/ Antimatter - Atom Smasher Makes New Discovery
An atom smasher based near Geneva, Switzerland conducted an experiment recently and found that there may be bits of matter that don't mirror the behavior of their antimatter counterparts.
This observance is unexpected, in that scientists have operated under the theory the universe started off with roughly equal amounts of matter and antimatter where particles of antimatter have the same mass of their twins but an opposite charge. They theorized that over the ensuing 14 billion years, most of the antimatter was destroyed, leaving a leftover universe of mainly matter.
After many experiments, in Switzerland, using the Large Hadron Collider, the 17-mile (27 km) circular particle accelerator, researchers are reporting that some matter particles produced inside the machine appear to be behaving differently from their antimatter counterparts, which might provide a partial explanation to the mystery of antimatter.
Roughly equal amounts of matter and antimatter are created in the collision of energetic gold nuclei inside the particle accelerator dubbed RHIC, but because the fireball expands and cools quickly, antimatter can survive longer than that created in the big bang. In this collision an ordinary helium-4 nucleus (background) is matched by a nucleus of antihelium-4 (foreground). Image Credit: STAR Collaboration and Lawrence Berkeley National LaboratoryThis excerpted and edited from LiveScience.com -
Is the New Physics Here? Atom Smashers Get an Antimatter Surprise
By lt | LiveScience.com
One potential explanation for this outcome is called "charge-parity violation." CP violation means that particles of opposite charge behave differently from one another.
The LHCb researchers found preliminary evidence that this is happening when particles called D-mesons, which contain "charmed quarks," decay into other particles. The whimsically named charmed quarks, like many exotic particles, are so unstable, they last only a fraction of a second. They quickly decay into other particles, and it is these products that the experiment detects. ("LHCb" is short for LHC-beauty, another flavor of quark.)
From the experiment, the researchers found a 0.8 percent difference in the probabilities that the matter and antimatter versions of these particles would decay into a particular end state.
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The new finding ranks as a "3.5 sigma" result, meaning the statistics are solid enough that there is only a 0.05 percent likelihood that the pattern they see isn't really there. For something to count as a true discovery in particle physics, it must reach a 5 sigma level of confidence.
"It's certainly exciting, and certainly worth pursuing," LHCb researcher Matthew Charles of England's Oxford University told LiveScience. "At this point it's a tantalizing hint. It's evidence of something interesting going on, but we're keeping the champagne on ice, let's say."
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If the finding is borne out, it would be a big deal, because it would mean the reigning theory of particle physics, called the Standard Model, is incomplete. Currently the Standard Model does allow for some minor CP violation, but not at the level of 0.8 percent. To explain these results, scientists would have to alter their theory or add some new physics to the existing picture.
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One possible example of the kind of new physics that might explain such CP violation is called supersymmetry. This theory suggests that in addition to all the known particles, there are supersymmetric partner particles that differ by half a unit of spin. Spin is one of the fundamental characteristics of elementary particles.
So far, no one has found direct evidence of supersymmetry. But if supersymmetric particles exist, they might be created instantaneously and disappear again during the particle-decay process. That way they could interfere with the decay process, potentially explaining why matter and antimatter decay differently.
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