Scientists celebrate the long-awaited discovery of the odderon, a strange phenomenon that rarely occurs when protons collide at high energies, such as particle accelerators. Although the odderon was predicted to exist in the early 1970s, it was not until recently that physicists finally gathered the data they needed from CERN’s Large Hadron Collider to confirm a true discovery.
The discovery contributes to physicists’ understanding of how all matter in the universe interacts at the smallest levels. Unlike celebrities Higgs boson, which was officially discovered in 2012, the odderon is not exactly a particle. Instead, it is the name of a three-gluon compound that is exchanged between protons (or a proton and its antimatter twin, the antiproton) when they collide violently but are not destroyed. Gluons are subatomic particles so called because they “stick” other particles called quarks; Quarks are the little things that make up the largest particles, like protons and neutrons, that make up the atoms we all know and love.
Gluons are fun because they don’t like being alone; they are almost always together. When it comes to an even group of gluons (two, four, etc.), we call it pomeron. When the number of gluons in the group is odd (three, five, etc.), well, you guessed it: this is an odderon. Odderó, for mysterious reasons, occurs very rarely, and although evidence has emerged over the decades, the evidence has never been strong enough to say it existed for sure. But the generally accepted theory of quantum physics says odderons it should they exist, so scientists have continued to look for them.
An international team of physicists announced earlier this month that their data reached a level of statistical significance known as “five sigma,” a threshold that most scientists agree means you can be at 99,999+ % sure you really made a discovery. After all, it’s not that physicists can just look inside their particle collider and see how an odderon smiles at them. Instead, they have to go through a surprising amount of recorded data when protons and antiprotons bounce off the walls of their detectors.
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If you put all this data on CDs and stack them on top of each other, “you’ll cover more than the distance between the Earth and the Moon,” said Christophe Royon, a professor of physics and astronomy at the University of Kansas. the team behind the new research. “You are collecting a lot of data. And then you have to do an analysis to identify, among all this data, what interests you. ”
Where protons and antiproton strike the detector after they have crashed into each other, the researchers explain how the particles interacted when they collided. Physicists classify records of millions and millions of these collisions, looking for enough suitable data points to be able to say with certainty that what they see could only be explained if the odderon exists. If they continued this research for years and never found evidence of the odderó, they would have to go back to the drawing board and present a new theory of how the universe works.
Fortunately, the researchers were able to collect their results from the particle colliders before the covid-19 pandemic stopped work in person, and then the analysis of the data could be done remotely. But they have not yet been able to celebrate together.
“With the covid situation, it’s a little tricky: everyone works from home, etc.,” Royon said in a video call. “But when we get back to normal, I think we deserve a party.”
The research included a careful comparison of data sets: one created a decade ago in the DØ experiment now closed at Fermilab in Illinois and others conducted in 2015, 2019 and 2020 (before the pandemic blockages) in the experiment. TOTEM of the Large Hadron Collider The Fermilab experiment collided with protons and antiprotons, while the LHC work examined protons that struck protons. It was by comparing the data of these two different colliders that they could be so sure of the existence of the odderon.
Although the team, which involved researchers from countries around the world, suspected it had something big last year, they didn’t want to rush any announcements. They asked independent researchers in the field to check their work if there were possible biases or problems before making their work public. Now the article is published as prepress by CERN and Fermilab and has been sent to the journal Physical Review Letters.
“The odderon is a solid prediction of the theory of strong interactions, made almost half a century ago,” said physicist Yuri Kovchegov of Ohio State University, who did not participate in the new work. “At the same time, it has been avoiding experimental detection for decades. The new result DØ and TOTEM, if maintained, is likely to indicate that the odderó has finally been found ”.
Kovchegov said in an email that the document “appears to be the first solid experimental evidence of the odderon’s existence,” although he would still like to see more experiments confirming the finding. He said next Electronic ion collider, a major new experiment that will be built in New York and open in the early 2030s, could answer ongoing questions about the odderon.
Royon agrees that the work of studying the odderon is far from over. “It’s not something we close and say we’re happy, finished, done,” he said. “In physics, when you find something new, it’s usually a door that opens up completely new domains.”