Neutrino study points to unknown force

McFarland

team of physicists lead by Kevin McFarland, assistant professor of physics and astronomy, appears to have uncovered a flaw in the "standard model" of matter that for the last 30 years has successfully explained the workings of the universe.

Their measurements indicate a surprising 1 percent discrepancy between predictions for the behavior of neutrinos and the way the elusive subatomic particles actually behave.

The findings, announced at Fermilab, the accelerator that runs at the world's highest energy levels, could mean that the physicists have observed an unknown force of nature or an undiscovered particle that is influencing the neutrinos.

"One percent may not seem a big difference," says McFarland, "but the measurement is so precise that the probability the predictions are right, given our result, is only about 1-in-400."

One of the fundamental particles that make up the universe, neutrinos carry no charge, unlike positively charged protons or negatively charged electrons. So the only thing that effects them is the "weak force"--a force whose effects are usually seen inside the nucleus of an atom.

Working over eight years at Fermilab, which is operated by Universities Research Association, Inc. under a contract with the U.S. Department of Energy, McFarland and his team observed millions of interactions of the highest energy, highest intensity neutrinos ever produced.

Neutrinos have surprised particle physicists before, but the new data leaves the experimenters wondering if their neutrinos were acted upon by a new force previously unobserved in nature or if there is some undiscovered particle influencing neutrino interactions.

Physicists in the United States, Japan, and Europe are planning a next generation of neutrino experiments that may solve this newly uncovered puzzle--or that may lead to a deeper understanding of how forces of nature interact.

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