CERN: The LHC Discovery of “New Physics” Particles Last December Were a Mirage

 

 

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Last December CERN announced a collection of unexpected observations at the Large Hadron Collider. Scientists quickly submitted over 500 papers, each inventing a new way to explain the observations, which seemed to challenge the foundations of the long-standing but tottering Standard Model. Now, in a new paper uploaded last night, CERN makes it clear that the exciting December measurements were mere statistical blips, flips of the hadron coin so to speak.


The particle accelerator ramped up to its fastest, most energetic collisions yet in 2015, with initially surprising results. Two different experiments (ATLAS and CMS) examine the products of collisions for new and unexpected physics—each serving as a check on the other. And in December, both teams reported the exact same thing: more pairs of photons with a combined energy of 750 gigaelectronvolts than expected. No particle or process in the Standard Model could explain the anamoly of the extra photons. The proponents of a New Physics buzzed: surely the new world of the dark universe was soon to be revealed.

Despite the discovery of the existence of the Higgs Boson on July 4, 2012 at the Large Hadron Collider in Geneva, puzzling questions about the nature of the universe remain unanswered. For example, the essential properties of neutrinos are still a mystery. And dark matter and dark energy, which together constitute 95 percent of the universe, are today still astonishing enigmas. The Higgs particle is unlike any other particle we have ever encountered. Why is it different? Are there more? Neutrinos are very light, elusive particles that change their identity as they travel. How do they fit into our understanding of nature? Are there new hidden dimensions of space and time?

Known particles constitute 1/6 of all the matter in the universe. The rest we call dark matter. But what is it? Can we detect these particles in our labs? Are there other undiscovered particles in nature? There are four known forces in nature. Are these manifestations of a single unified force? Are there unexpected new forces? Both matter and anti-matter were produced in the Big Bang, but today our world is composed only of matter. Why? Why is the expansion of the universe accelerating?

 

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A similar red herring event occured in 2012 when the LHC to reach previously unachieved energies, the accelerator started up again after improvements, and ATLAS and CMS both saw extra photons summing to 125 gigaelectronvolts. Teams searched again a few months later to check their results—and continued to see photons at the exact same energy. They were definitely observing a brand-new particle. At the time, though, there remained a single unconfirmed piece of the Standard Model: ATLAS and CMS had found the Higgs boson, the final piece of the puzzle. The Higgs is a huge step toward understanding how particles acquire mass—and measured “theta one-three”—an important number that may lead to a better understanding of neutrino properties and nature’s imbalance between matter and antimatter.

But, unlike the Higgs discovery, the photons announced in December 2015 were a blip of particularly interesting noise. “This is pretty unfortunate,” theoretical physicist Michele Redi wrote Wired in an email, “as it would have been the greatest discovery in several decades in our field.”

It seems likely that with the Higgs, we’re seeing only the tip of the iceberg. The Higgs field seems to give mass to just some particles; others are still complete mysteries. Meanwhile, we’re working to understand why there’s matter and not antimatter everywhere we look. What’s more, there are particles out there like neutrinos about which we are still almost completely ignorant. And then there’s the elephant in the room—the “dark universe” of dark matter and dark energy.

The Daily Galaxy via CERN, Symmetry.org, Wired.com

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