Hopes for brand spanking new physics dashed by ordinary-looking W bosons at CERN

A doable crack in the usual mannequin of particle physics appears to be shrinking, as new information from CERN’s Giant Hadron Collider (LHC) contradicts a earlier puzzling end result that had physicists enthusiastic about the opportunity of new, unique physics – however some mysteries stay.

“The standard model survives for the moment,” Josh Bendavid on the Massachusetts Institute of Know-how informed a packed seminar room at CERN, the particle physics laboratory close to Geneva, Switzerland, on 17 September. He was presenting new information on the mass of the W boson, a elementary particle that’s essential for processes like nuclear decay and setting the mass of the Higgs boson.

Questions in regards to the W boson mass started in 2022, when physicists working with information from the Tevatron collider at Fermilab in Illinois despatched shockwaves by the particle physics group. Their worth for the W boson mass was starkly completely different from that predicted by the usual mannequin, our greatest image of how the universe’s particles and forces work together, suggesting physicists could have missed one thing.

However in 2023, researchers at CERN solid doubt on this discrepancy, after they reanalysed outdated information taken by the ATLAS detector on the LHC. They discovered a price for the W boson mass that when once more agreed with the usual mannequin prediction, dampening hopes for a deviation from recognized physics.

Now, Bendavid and his colleagues have produced a brand new worth for the W boson mass, utilizing new information from one other of the LHC’s detectors, the Compact Muon Solenoid (CMS), and located a price of 80,353 million electronvolts (MeV) which, with an uncertainty of 6 MeV, agrees with the usual mannequin. The tiny uncertainty additionally makes this probably the most exact measurement produced on the LHC, stated Bendavid.

Ashutosh Kotwal at Duke College in North Carolina, who led the scientific collaboration that produced the Tevatron end result, says that it’s nice to have one other measurement of the W boson mass, however because the LHC and Tevatron colliders use completely different strategies to supply the particle, it’s tougher to match the outcomes.

“In this fundamental respect of the beams, ATLAS and CMS are identical,” says Kotwal. “What would have been ideal is additional or independent data at the Tevatron.” Sadly, the Tevatron shut down in 2011, so there might be no extra new information.

All of this implies it’s too early to inform which W boson mass measurement is appropriate and that the variations should nonetheless be defined. “It doesn’t end with two numbers on the table, it’s the beginning,” says Kotwal. “It’s when we start discussing scientific and technical details about procedures. The truth is out there, there is a W boson mass in the universe. We’re all trying to find it.”