“Mystery”: New particle measurement contradicts our understanding of the universe, scientists say

After a decade of painstaking measurements, scientists announced Thursday that a fundamental particle — the W particle — has significantly greater mass than the theory, shattering the foundations of our understanding of how the universe works.

Those foundations are based on the Standard Model of particle physics, the best theory scientists have for describing the most basic building blocks of the universe, and what forces control them.

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

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

Ashutosh Kotwal, a physicist at Duke University who led the study, said the result took more than 400 scientists more than 10 years to capture and investigate a “data set of about 450 trillion collisions.”

These collisions — created by hitting the particles together at astonishing speeds to study them — were made by the Tevatron collider in Illinois.

Technicians working on Collider Detector
Technicians perform maintenance on the central part of the Collider Detector at Fermilab. Fermi National Accelerator Laboratory is home to the Tevatron.

© CORBIS/Corbis via Getty Images


It was the world’s most energetic particle accelerator until 2009, when it was supplanted by the Large Hadron Collider near Geneva, which made the famous sighting of the Higgs boson a few years later.

The Tevatron stopped running in 2011, but the scientists at the Collider Detector at Fermilab (CDF) have been cracking numbers ever since.

“Extraordinary Claims Require Extraordinary Evidence”

Harry Cliff, a particle physicist at Cambridge University who works on the Large Hadron Collider, said the Standard Model is “probably the most successful theory and scientific theory ever written down — it can make fantastically accurate predictions.”

But if those predictions turn out to be wrong, they can’t just be adjusted.

“It’s like a house of cards, you pull on it a little too much and the whole thing collapses,” Cliff told AFP.

But the standard model is not without its problems.

For example, it doesn’t take into account dark matter, which is thought to make up 95 percent of the universe.

In addition, “a few cracks have been uncovered in the Standard Model recently,” physicists said in an accompanying Science article.

“In this context of clues that there are pieces missing from the Standard Model, we have contributed another very interesting and somewhat large clue,” Kotwal told AFP.

Jan Stark, physicist and research director at the French CNRS Institute, said that “this is either a big discovery or a problem in data analysis”, and he predicts “pretty heated discussions in the coming years”.

He told AFP that “extraordinary claims require extraordinary evidence”.

“A new fundamental ingredient”

The CDF scientists said they had determined the mass of the W boson with a precision of 0.01 percent — twice as accurate as previous attempts.

They compared it to measuring a gorilla’s weight from 350 kilograms (800 pounds) to 40 grams (1.5 ounces).

They found that it was different from the Standard Model’s prediction by seven standard deviations, also known as sigma.

Cliff said that if you toss a coin, “the chance of getting a five sigma result by luck is one in three and a half million.”

“If this is real, and not a systematic bias or misunderstanding of how the calculations should be done, then that’s a huge problem because it would mean there’s a new fundamental ingredient in our universe that we haven’t discovered before. “

However, he added that “if you’re going to say something big like we’ve broken the Standard Model of particle physics, and there are new particles to discover, to convince people that you probably need more than one measurement of more than one measurement.”

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

And after a decade of measurements, Kotwal is not finished yet.

“We’re following the directions and leaving no stone unturned, so we’ll find out what this means.”

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