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At the Compact Muon Solenoid (CMS<\/a>) near Geneva, Switzerland, researchers pulled about 100 million W decays from more than a billion collisions.<\/p>\n Working at the Massachusetts Institute of Technology (MIT<\/a>) Kenneth Long helped turn those tracks into a mass.<\/p>\n That ten-year push by the MIT team targeted the heavy result, which made unseen particles look newly plausible.<\/p>\n Now the story turns from crisis to the deeper question of why this mass matters.<\/p>\n Why W boson mass matters<\/p>\n Inside the Standard Model, physicists\u2019 framework for known particles and forces, the W mass is tied to several other masses.<\/p>\n Mass matters because the W boson, found in 1983, carries the weak force<\/a> \u2013 the interaction behind radioactive decay and stellar fusion.<\/p>\n If some unknown particle nudges this balance through quantum loops, fleeting effects from virtual particles, the W mass should move.<\/p>\n So this measurement was less about one number than about checking whether the theory still holds under pressure.<\/p>\n The outlier problem<\/p>\n Back in 2022, the Collider Detector at Fermilab (CDF<\/a>) reported 80,433.5 MeV with a 9.4 MeV uncertainty.<\/p>\n Elsewhere, other collider results had clustered lower, so the mismatch looked less like noise and more like a real problem.<\/p>\n According to the global electroweak fit, a combined check of precision data, the expected value sat near 80,353 MeV.<\/p>\n With that number in hand, CMS did not erase the puzzle overnight, but it narrowed the room where any new effect could hide.<\/p>\n Chasing a ghost<\/p>\n Almost as soon as it appears, the W boson breaks apart, leaving researchers to reconstruct a particle<\/a> that does not stay put.<\/p>\n One product is a neutrino, a hard-to-catch particle that slips through the detector without leaving a direct signal.<\/p>\n Meanwhile, the other product is a muon, a heavier cousin of the electron, whose curved path can actually be measured.<\/p>\n So the team had to infer one missing piece from the visible one, which set up the harder work.<\/p>\n Reading the curves<\/p>\n Inside CMS, a powerful magnetic field bent each muon\u2019s path, and more bend meant less momentum.<\/p>\n Because the parent W boson was also moving, the researchers<\/a> had to separate motion from mass before trusting any answer.<\/p>\n To do that, they built about 4 billion simulated events and compared those patterns with data from the 2016 collider run.<\/p>\n Only when the simulated and real muon shapes lined up could the particle\u2019s mass be read with confidence.<\/p>\n Making precision stick<\/p>\n Precision lived or died on muon calibration, so the team tuned the detector against well-known particle decays before reading the result<\/a>.<\/p>\n Those landmarks let tiny drifts in alignment, material, and field strength stand out before they could distort the answer.<\/p>\n Even then, the largest remaining errors came from muon momentum and from the proton\u2019s internal makeup, not from simple counting.<\/p>\n Reaching a total uncertainty of 9.9 MeV put CMS in the same precision class as the widely discussed CDF result.<\/p>\n Where the number lands<\/p>\n When the fit settled, the mass came out to 80,360.2 MeV, just seven MeV above the theory-based global expectation.<\/p>\n Closer agreement with theory left it far from the CDF number that had stirred so much speculation.<\/p>\n Other collider results had mostly landed in the same neighborhood, making the old discrepancy look more isolated once the CMS number arrived.<\/p>\n What it cannot solve<\/p>\n Yet the result does not turn the Standard Model into a finished description of nature.<\/p>\n Dark matter still lacks a known particle inside the theory, and the early universe still produced more matter than antimatter.<\/p>\n Closing the W gap therefore removed one possible crack, but it left the bigger missing pieces exactly where they were.<\/p>\n For that reason, precision work matters because every stubborn agreement narrows where a truly new idea can still fit.<\/p>\n The next measurement<\/p>\n Next, the collaboration plans to add more data and tighten the analysis rather than declaring the case closed.<\/p>\n Future runs can cut statistical noise, while better control of detector alignment and the proton\u2019s internal structure could squeeze the remaining uncertainty.<\/p>\n Still, the group stopped well short of declaring victory because a cleaner measurement<\/a> could reveal a smaller mismatch later.<\/p>\n \u201cThis new measurement is a strong confirmation that we can trust the Standard Model,\u201d Long said.<\/p>\n Order without closure<\/p>\n The new W boson mass did not rewrite physics, but it restored agreement among measurements that must fit together.<\/p>\n By closing in on one disputed number, researchers strengthened the guide they use to hunt whatever still lies beyond it.<\/p>\n The study is published in Nature<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Researchers have measured the mass of the W boson, a fundamental particle that carries the weak force responsible…\n","protected":false},"author":2,"featured_media":386248,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[85,46,141],"class_list":{"0":"post-386247","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-il","9":"tag-israel","10":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/386247","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=386247"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/386247\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/386248"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=386247"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=386247"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=386247"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}