The Large Hadron Collider (LHC), a huge particle accelerator, continues to push the boundaries of science, and in recent experiments with its participation, scientists have discovered something that may be the first potential evidence of the existence of a subatomic quasiparticle called odderon, which until then existed only in theory … The results obtained concern hadrons, a family of elementary particles, which includes protons and neutrons, which are composed of quarks "glued together" with gluons.
In their experiments with the LHC, scientists used a special mode of operation of the accelerator, in which the colliding protons remain intact, rather than being destroyed, generating whole showers of secondary particles. Earlier, when conducting similar experiments, it was noticed that in such collisions, protons not only fly away from each other, they manage to very quickly exchange several gluons. In this case, the number of "exchange" gluons was always even before.
In the end, scientists did not find the odderon itself, but the researchers observed certain effects that could indicate its presence. Physicists used protons, which have high energy, which allowed them to obtain greater accuracy in their measurements. And in the results of these measurements, cases of exchange between protons with an odd number of gluons were found, which does not at all fit into all existing models of such processes. The researchers believe that it is the odderon, a quasiparticle consisting in this case of three, five, seven or more odd numbers of gluons, that is responsible for this discrepancy, which is formed for a short time at the moment of collision of protons.
“The results obtained do not break the existing Standard Model of particle physics. There are a number of "dark spots" in this model, and our work allowed us to "illuminate" only one of these areas and add another new detail to it, "says particle and subelemental particle physicist Timothy Raben of the University of Kansas.
For the searches, the highly sensitive sensors of the TOTEM experiment were used, installed at four key points in the collider tunnel, where the proton beams "cross" and billions of collisions occur every second.
“One possible explanation for why protons can collide without destruction is odderon, but in practice, scientists have never observed this. This may be the first time that real proof of the existence of these quasiparticles has been obtained,”comments Simona Giani, a spokesman for a group of physicists working with the TOTEM experiment, which is part of a general search for quasiparticles.
It is rather difficult for a layman to understand this, so scientists explain this using the example of an auto transporter transporting cars in a trailer.
“Imagine that the protons are two large tractors carrying cars. These are often seen on the road,”explains Raben.
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“Now imagine that these two trucks collide with each other, however, after the accident, the trucks remain intact, but the cars that they transported will scatter in different directions. And at the same time, new cars are literally formed in the air. Energy passes into a state of matter."
“Physicists have been hunting theoretical odderons for the past few decades, starting in the 1970s. However, the technological capabilities of the time simply did not provide evidence of the existence of the Odderons,”adds Raben.
More than 100 scientists from eight countries were involved in the experiments to find odderons. Billions of proton pairs were accelerating inside the LHC every second. Thanks to the modernization of the hadron collider in 2015, the peak energy level of the accelerated protons was 13 TeV.
Although researchers have not been able to directly observe odderon, they have witnessed its effects and hope to get more transparent results in the future. Scientists believe that the next modernization of the LHC will allow them to be obtained, which will allow accelerating particles to even higher energy indicators.
“We expect great results in the next few years,” commented Christophe Royon of the University of Kansas.
The results of the current work were published on the ArXiv.org website and are currently awaiting evaluation by other experts.
Nikolay Khizhnyak