Skip to content


After a decade of meticulous measurements, scientists have announced that a fundamental particle – the W boson – has a mass significantly greater than theoretical, shaking the foundations of our understanding of how the universe works.

These foundations are based on the Standard Model of particle physics, which is the best theory available to scientists for describing the most basic building blocks of the universe and the forces that govern them.

The W boson is an electrically charged fundamental particle that governs what is called the weak force, one of the four fundamental forces of nature, and therefore a pillar of the Standard Model.

However, the most accurate measurement of the W boson ever made directly contradicts the rules of the Standard Model, according to a new study published in the journal Science.

Ashutosh Kotwal, a Duke University physicist who led the study, said the result took more than 400 scientists over 10 years to record and review a “dataset of approximately 450 trillion collisions”.

These collisions – made by smashing particles together at mind-blowing speeds to study them – were made by the Tevatron collider in the US state of Illinois.

It was the highest-energy particle accelerator in the world until 2009, when it was supplanted by the Large Hadron Collider near Geneva, which observed the Higgs boson a few years later.

The Tevatron stopped working in 2011, but scientists at Fermilab’s Collider Detector (CDF) have been making calculations ever since.

Harry Cliff, a particle physicist at the University of Cambridge who works at the Large Hadron Collider, said the Standard Model was “probably the most successful theory and scientific theory ever written – it can make incredibly accurate predictions”.

But if those predictions turned out to be wrong, they simply couldn’t be changed.

“It’s like a house of cards, you pull too much on it, it all comes crashing down,” Cliff said.

But the standard model is not without its problems. For example, it does not take into account dark matter, which would represent 95% of the universe.

On top of that, “a few cracks have recently been exposed in the Standard Model,” the physicists said in a companion Science paper.

“Within this framework of clues that the standard model is missing parts, we have provided an additional clue, which is very interesting and quite important,” Kotwal said.

Jan Stark, physicist and research director at the CNRS, declared “that it is either a major discovery or a problem in the analysis of the data”, predicting “quite heated discussions in the years to to come”.

“Extraordinary claims require extraordinary evidence,” he said.

CDF scientists said they determined the mass of the W boson with an accuracy of 0.01%, twice as accurate as previous efforts.

They compared it to measuring the weight of a 350 kg (800 lb) gorilla at less than 40 grams (1.5 ounces).

They found that it differed from the Standard Model prediction by seven standard deviations, also known as sigma.

Cliff said that if you tossed a coin, “the odds of getting a five sigma result by stupid luck are one in three and a half million”.

“If this is real, and not a systematic bias or a misunderstanding of how to do the math, then that’s a big deal because it would mean there’s a fundamental new ingredient in our universe that we don’t have. discovered before.”

However, he added: “If you’re going to say something as important as we’ve broken the standard model of particle physics, and there are new particles to be discovered, to convince people of that, you you probably need more than one measure more than one measure.

CDF co-spokesman David Toback said: “It is now up to the theoretical physics community and other experiments to follow this and shed some light on this mystery.”

And after a decade of measures, Kotwal is not done yet.

“We’re following the clues and leaving no stone unturned, so we’ll figure out what that means.”

Not all news on the site expresses the point of view of the site, but we transmit this news automatically and translate it through programmatic technology on the site and not from a human editor.