Mysterious Particles Coming From the Ground in Antarctica Have Physicists Puzzled

Thursday, 27 September 2018 - 11:45AM
Earth
Thursday, 27 September 2018 - 11:45AM
Mysterious Particles Coming From the Ground in Antarctica Have Physicists Puzzled
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Image Credit: Pixabay Composite
The most basic thing we know about cosmic rays are that they are supposed to enter the Earth from space, not the other way around. LiveScience reports that as early as March 2016, researchers in Antarctica using NASA's Antarctic Impulsive Transient Antenna (ANITA) have been baffled by high-energy particles going through the ice in the wrong direction. The "large cross-sections" of the rays should prevent them from entering the Earth on one side and making it all the way through to the other. A new paper [PDF] from astrophysicists at Penn State University has added to the mystery and the possible shattering of modern physics models because it reveals that similar backwards particles were also picked up by another antenna in three events not previously linked to the ANITA findings.

"I was like, 'Well this model doesn't make much sense,'" lead author Derek Fox told LiveScience about when he first saw the ANITA data earlier this year. It was an attempt to find better explanations than the ones published at the time that led Fox and his colleague and co-author Steinn Sigurdsson to the new discovery using data from the IceCube Neutrino Observatory at the Amundsen–Scott South Pole Station in Antarctica. Like the ANITA findings, the upward particles found in the IceCube data challenge the Standard Model (SM) that physicists have looked to for decades, which is a big deal. "That's what really got me going, and looking at the ANITA events with the utmost seriousness," Fox said. "This is what physicists live for. Breaking models, setting new constraints [on reality], learning things about the universe we didn't know."

"It was clear from the start that if the ANITA anomalous events are due to particles that had propagated through thousands of kilometers of Earth, then those particles were very likely not SM particles," said Niels Bohr Institute astrophysicist Mauricio Bustamante, who was not involved with Fox and Sigurdsson's research. "The paper that appeared today is the first systematic calculation of how unlikely is that these events were due to SM neutrinos. Their result strongly disfavors a SM explanation." The researchers argue that non-SM neutrinos may be a kind of supersymmetric particle called stau sleptons. But supersymmetry is still theoretical, so more research and data would be needed to prove that position. "As an observer, there's no way that I can know that this is a stau," Fox said about the already contested idea.
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