After conducting a diligent seek for a hypothetical subatomic particle — the “sterile neutrino” — that might have crammed in one other clean of the Customary Mannequin of particle physics, scientists at a particle detector within the South Pole are actually nearly sure that such a particle doesn’t exist.
Three varieties, or flavors, of neutrinos are already recognized to science and are a part of the Normal Mannequin; they’re known as muon, electron and tau. Neutrinos have virtually no mass and infrequently work together with matter, making them tough to detect. As an illustration, billions of neutrinos cross via Earth and even your physique each minute however nobody feels a factor. The three identified flavors have been detected as a result of they’re charged with weak nuclear interplay — one of many 4 basic forces of the Normal Mannequin.
Experiments have hinted at a fourth taste, nicknamed the sterile neutrino — a hypothetical particle that might not work together with matter in any respect, besides possibly by gravity. Discovery of the particle might assist not simply resolve the thriller behind the origin of darkish matter, which makes up greater than 1 / 4 of the mass and vitality within the observable universe, it might additionally clarify the asymmetry between matter and antimatter within the Universe, and would have additionally totally upset the Normal Mannequin.
The one method to observe a sterile neutrino can be to catch it within the technique of transformation into one of many different three flavors. In a examine revealed Monday within the journal Bodily Overview Letters, researchers stated they discovered no hint of the particle “in both of two independently developed analyses, every utilizing one yr of atmospheric neutrino information.”
The info was collected on the IceCube Neutrino Observatory, an Antarctic laboratory half below ice, by “utilizing so-referred to as atmospheric neutrinos, neutrinos created when cosmic rays crash into particles within the higher ambiance of the Earth.” Scientists concluded with ninety nine % certainty that sterile neutrinos don’t exist.
Francis Halzen, a College of Wisconsin-Madison professor of physics and principal investigator for the IceCube Neutrino Observatory, stated in a press release: “Like Elvis, folks see hints of the sterile neutrino in all places. There was this assortment of hints, and theorists had been satisfied it exists.”
With the brand new research, IceCube scientists have positioned “sturdy limits on the attainable existence of a sterile neutrino,” in accordance with David W. Schmitz from the College of Chicago, who was reacting to the examine in the identical journal.
Three months in the past, in Could, IceCube scientists had precluded one other chunk of the “parameter area” for locating neutrinos. With the brand new paper, scientists are nonetheless no nearer to discovering out why neutrinos have mass, a key to understanding many mysteries of the universe.
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