PHYSICS PROFESSOR: SLIGHT FLAW IN STANDARD MODEL OF MATTER

 

McFarland

The standard model used for the past 30 years to explain the workings of the universe may be slightly flawed and require revision, according to a new study led by Kevin McFarland, assistant professor of physics and astronomy.

Working for the past eight years at the world's most advanced high-energy accelerator at Fermilab, McFarland and his team made precise measurements of the forces affecting subatomic particles known as neutrinos and discovered a critical 1 percent difference from what standard theories had predicted.

The findings, published in Physical Review Letters, may mean that an unknown force or undiscovered particle could be influencing neutrinos.

"One percent may not seem a big difference," McFarland says. "But the measurement is so precise that the probability that we're wrong is only 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, and rarely interact with other particles. Long thought to be immeasurable, neutrinos are so insubstantial that they can pass through nearly all physical bodies undetected.

According to standard subatomic theories, only the "weak force"-a force that exists inside atoms-is known to influence neutrinos.

Using the Fermilab accelerator, McFarland and his team members were able to measure the rate at which neutrinos interacted with other subatomic particles. They discovered that neutrinos collided with other particles 1 percent less often than expected, leading to the hypothesis that an as-yet unidentified force also may be
at work.

Experimenters using a particle accelerator in Switzerland recently measured the same interaction in a different particle reaction with similar precision. They observed the same discrepancy, however, with less certainty.

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