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Physicists at CERN find evidence of pentaquarks

意得辑专家视点 | 2015年7月15日 | 1,221 浏览次数

The researchers at the Large Hadron Collider (LHC) at CERN near Geneva have discovered a new class of particles called ‘pentaquarks.’ The tiny ingredients of sub-atomic particles such as protons and neutrons are called quarks. Protons and neutrons are made of three quarks. The existence of a five-quark version, or "pentaquark," was theorized by American physicist Murray Gell-Mann in 1964, but it was never found. Physicists on LHCb team found pentaquarks through observing a signal that showed an unexpected appearance of two short-lived objects weighing 4.38 and 4.45 gigaelectronvolts (4.67 and 4.74 times heavier than a proton) during the decay of trillions of subatomic particles known as ‘Lambda B’ baryons, by analysing data that were recorded between 2009 and 2012. Announcing the discovery, the LHCb spokesperson, Guy Wilkinson, said, “The pentaquark is not just any new particle — it represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons and neutrons, in a pattern that has never been observed before. Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we’re all made, is constituted.” Although the researchers have high confidence in their finding, they caution that the results are still preliminary.       

Read more in Nature


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