New data contradicts accepted standard model of particle physics

The uncertainty of science: After years of analysis, physicists have refined their measurement of the mass of one important subatomic particle, and discovered that its weight violates the accepted standard model of particle physics, threatening to overthrow it entirely.

W bosons are elementary particles that carry the weak force, mediating nuclear processes like those at work in the Sun. According to the Standard Model, their mass is linked to the masses of the Higgs boson and a subatomic particle called the top quark. In a new study, almost 400 scientists on the Collider Detector at Fermilab (CDF) collaboration spent a decade examining 4.2 million W boson candidates collected from 26 years of data at the Tevatron collider. From this treasure trove, the team was able to calculate the mass of the W boson to within 0.01 percent, making it twice as precise as the previous best measurement.

By their calculations, the W boson has a mass of 80,433.5 Mega-electronvolts (MeV), with an uncertainty of just 9.4 MeV either side. That’s within the range of some previous measurements, but well outside that predicted by the Standard Model, which puts it at 80,357 MeV, give or take 6 MeV. That means the new value is off by a whopping seven standard deviations.

Further cementing the anomaly, the W boson mass was also recently measured using data from the Large Hadron Collider, in a paper published in January. That team came to a value of 80,354 MeV (+/- 32 MeV), which is comfortably close to that given by the Standard Model.

Personally, I always take this level of physics with a great deal of skepticism. The data involves a lot of assumptions and uncertainties. That other researchers came up with a different number illustrates this.

Nonetheless, these results could suggest that the standard model, the consensus theory for decades, is either incomplete, or wrong. The former would be more likely, but no possibility should be dismissed. And even if wrong, much of that model still works so well any new model must include large parts of it.