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<\/div>The CMS detector at the Large Hadron Collider<\/p>\n
SciTech Image\/James King-Holmes\/Alamy Stock Photo<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
A possible crack in the standard model of particle physics seems to be shrinking, as new data from CERN\u2019s Large Hadron Collider (LHC) contradicts a previous puzzling result<\/a> that had physicists excited about the possibility of new, exotic physics<\/a> \u2013 but some mysteries remain.<\/p>\n \u201cThe standard model survives for the moment,\u201d Josh Bendavid<\/a> at the Massachusetts Institute of Technology told a packed seminar room at CERN, the particle physics laboratory near Geneva, Switzerland, on 17 September. He was presenting new data on the mass of the W boson, a fundamental particle that is crucial for processes like nuclear decay and setting the mass of the Higgs boson.<\/p>\n Questions about the W boson mass began in 2022, when physicists working with data from the Tevatron collider at Fermilab in Illinois sent shockwaves through the particle physics community. Their value for the W boson mass was starkly different from that predicted by the standard model, our best picture of how the universe\u2019s particles and forces interact, suggesting physicists may have missed something.<\/p>\n But in 2023, researchers at CERN cast doubt<\/a> on this discrepancy, after they reanalysed old data taken by the ATLAS detector at the LHC. They found a value for the W boson mass that once again agreed with the standard model prediction, dampening hopes for a deviation from known physics.<\/p>\n <\/p>\n Now, Bendavid and his colleagues have produced a new value for the W boson mass, using new data from another of the LHC\u2019s detectors, the Compact Muon Solenoid (CMS), and found a value of 80,353 million electronvolts (MeV) which, with an uncertainty of 6 MeV, agrees with the standard model. The tiny uncertainty also makes this the most precise measurement produced at the LHC, said Bendavid.<\/p>\n