Monday News Flash: New Evidence at CERN’s LHC Points to Existence of Higgs Particle

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The ATLAS detector at the LHC, located near Geneva, Switzerland, has found an unexpected abundance of pairs of W bosons, which carry the weak nuclear force, with energies between about 120 to 140 gigaelectronvolts (GeV). The new excesses, reported on Friday by Kyle Cranmer of New York University at the Europhysics Conference in Grenoble, France, have been vetted by the both ATLAS and CMS collaborations.

This new finding could be due to a Higgs particle with a mass in that range decaying into pairs of W bosons –particle masses and energy are treated interchangeably because mass is readily converted into energy in particle collisions and decays. The team also observed smaller excesses in pairs of photons and Z bosons, which carry the weak nuclear force and could be due to Higgs' decays too.


The combined statistical significance, taking all three types of excess reported by ATLAS into account, is 2.8 sigma, slightly below the 3 sigma threshold (equivalent to a 1-in-370 chance of being due to a fluke) that a measurement must pass to count as "evidence" for something new: only 5 sigma data, equivalent to a 1-in-1.7 million chance of being due to a fluke, gains "discovery" status.

The other main detector at the LHC, the CMS, has found an excess in a similar range, between 130 and 150 GeV, reports Nature, or approximately 2 sigma.

“Discovery or exclusion of the Higgs particle, as predicted by the Standard Model, is getting ever closer,” said CERN's Director for Research and Scientific Computing, Sergio Bertolucci. “Both occurrences will be great news for physics, the former allowing us to start the detailed study of the Higgs particle, the latter being the first proof of the incompleteness of the Standard Model, requiring new phenomena to be happening within the reach of the LHC.”

The Daily Galaxy via CERN and newscientist.com

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