The most accurate measurement of the W boson so far produces a result that physicists do not understand

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A collaboration of hundreds of scientists has precisely measured the mass of the W boson, an elementary particle responsible for the weak nuclear force. The researchers found, to their surprise, that the boson is more massive than predicted since Standard model theory of particle physics which describes many of the fundamental forces of the universe.

The new value was derived from 10 years of experiments and calculations by 400 researchers in 54 different institutions around the world, an impressive effort. All data was collected from Fermilab Collider Detector experiments (CDF-II for short), from four floors high and 4,500 tons to the Tevatron accelerator near Chicago, Illinois.

The CDF Collaboration found that the mass of the W boson is 80.433 +/- 9 MeV / c ^ 2, a figure that is about twice as accurate as the previous measurement of its mass. To get an idea of ​​the scale, the new measurement places the W boson at about 80 times the mass of a proton. The results of the team to publish hoy it Science.

“The truth is, what happened here is what usually happens Most of the time in science. We looked at the number and said, ‘Hey, that’s weird‘”, She said David Toback, physicist at Texas A&M University and spokesperson for the CDF Collaboration, on video call. “You may see silent people. We didn’t know what to get out of That”.

“We were very pleasantly surprised [el resultado]Ashutosh Kotwal, a physicist at Duke University and a member of the CDF collaboration, wrote in an email. “We were so focused on the accuracy and solidity of our analysis that the value itself was like a wonderful scare.”

The W boson is associated with weak nuclear forcea fundamental interaction that is responsible for a type of dradioactive decay and of nuclear fusion occurring in the starsS. Do notand worry, Just because the boson has a very different mass than expected doesn’t mean we’ve completely misunderstood things like nuclear fusion, but it means there’s still a lot we don’t understand about the particles that make up our universe and how they interact together..

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“The standard model is the best we have for particle physics. It is incredibly good. The problem is, we know we’re wrong, “Toback said.” DFrom the scientists’ point of view, the experimenters are trying to say, “Damn, we can find something that the standard model does not provide correctly, which might give us a clue as to which is more true“.

The standard model predicts a value for the mass of the W boson, a value the team attempted challenge assessment 4 million candidate W bosons generated by proton-antiproton collisions at Fermilab. Your result is higher than the standard model prediction by as many as seven standard deviations. Kotwal, who has published five increasingly precise measurements of the particle’s mass over the past 28 years, said that “the odds of the 7 standard deviation increase being a statistical fluke are less than 1 in a billion.”

Toback compared the measurement with the weight measurement of a 30-foot gorilla.0 kg with a margin of error of 30 grams. As is the case with In many scientific experiments, especially in particle physics, where the masses are so small, the researchers blinded their results to make sure the calculations weren’t swayed by the research team’s expectations or hopes.

But now, with an extraordinarily precise measurement so different from previous lower estimates, physicists have the unenviable task of figuring out what the Standard Model does not account for. It is certainly not the first time that subatomic physics has shown itself to be different in reality from humanity’s best guesses. in April last yearthe Muon g-2 collaboration found further evidence that the properties of want (another subatomic particle) do not match with the provisions of the Standard Model. And two of the most important facts about our universe, gravity and dark matter, are not explained by the model.

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“To find out what the most fundamental theory might be, it is important to find phenomena that cannot be explained by the [modelo estándar]”, he wrote an email Claudio Campagnari, a physicist at the University of California – Santa Barbara who is not affiliated with the recent study. In other words, phenomena in which the approximation [del modelo estándar] pause. “Campagmari was co-author of a Perspectives article on the new measurement.

There are experiments set up to do just that; will test the implications of today’s discovery with several collision experiments. The results of ATLAS and del Compact Muon Solenoid (CMS), two detectors from CERN’s Large Hadron Collider (the two detectors responsible for the Discovery of the Higgs boson 10 years ago), are yet to come. And the large, high-brightness hadron collidera renewal which will increase the number of possible collisions by a factor of 10it will also increase the chances of seeing new particles once completed in 2027.

The CDF collisions were between protons and antiprotons, while the Large Hadron Collider produces proton-proton collisions. Kotwal said that if humans built an electron-positron collider, it would allow precise measurements and searches of rare processes that the Large Hadron Collider is unable to produce.

What did you say Martijn Mulders, a CERN physicist who co-wrote the Perspectives article, In an email, physicists will take a two-pronged approach to test the model: measuring known particles (such as the W boson) more accurately, as well as discovering entirely new particles.

The Tevatron Accelerator closed in 2011, shortly after the collaboration ended its experimental phase. So today’s result is something like an afterlife for it historical instrument, a victory for the team and particle physics as a whole.

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