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The particle accelerator at CERN discovered a rare particle with two heavy quarks; A scientist from Uni' Tel Aviv predicted its mass almost exactly

Prof. Mark Karliner from Tel Aviv University predicted the mass of the particle almost exactly three years ago together with a colleague from the USA. "Now it remains to check its decay rate and compare it to predictions"* The particle will allow us to know more details about the strong force

LHCb facility in Cerne, border of France and Switzerland. Photo: Avi Blizovsky
Explanatory poster at the LHCb facility in Cerne, border of France and Switzerland. Photo: Avi Blizovsky

Scientists at the Large Hadron Collider at CERN have detected a new type of particle whose existence was predicted theoretically but observed for the first time. The discovery will help researchers learn more about the so-called "strong force" that holds the centers of atoms together. The details about the particle known as ++Xi-cc (full explanation of the nickname below) were presented at the High Energy Physics Conference in Venice.

The research was carried out in the LHCb experiment led by Dr. Patrick Spradlin from the University of Glasgow. He said that the discovery "will shed light on a long puzzle and open a new and exciting branch of research." His colleague, Professor Paul Soler, also from the University of Glasgow, described the development as "a new frontier in understanding the strong force".

Almost all the matter we see around us consists of neutrons and protons, which form the centers of atoms. These are made up of three smaller particles called quarks which can be either light or heavy. There are, however, six different types of quarks which combine in different ways to create other types of particles. Those identified so far contain, at most, one heavy quark.
The research team will now measure the properties of Xi-cc++ to determine how this particle behaves and how the strong force holds the system together. They also expect to find more heavy quark particles.
Another unusual feature of the particle is that it has twice the positive charge of the proton and is also four times heavier. The researchers submitted an article reporting these findings to the journal Physical Review Letters.
Prof. Mark Karliner, professor of theoretical physics at the School of Physics and Astronomy at Tel Aviv University is a theoretical physicist who specialized in this field of particle physics.

"Particles of this type are distant cousins ​​of the proton and neutron which consist of three quarks and belong to a family called baryons. The bullions contain three quarks. In nature there are five types of quarks that can produce bullies, so there are lots of possible combinations. At the beginning of the twentieth century, scientists were able to 'see' baryons that consist of three light quarks - the proton and the neutron

"In the fifties and sixties, baryons were discovered to contain an additional quark, the s quark. Prof. Yuval Naaman, founder of the Physics Department at Tel Aviv University, gained worldwide fame when he discovered the correct classification of baryons consisting of the three quarks u, d and s, and with the help of this classification he successfully predicted the mass of the omega-minus baryon, which has the composition sss .”

There are two light and three heavy quarks, and any triplet you choose from the five can exist. However, the heavier the particles, "the more difficult it is to produce them in an accelerator because their creation requires more energy and they break down quickly. To date we have seen bullies that include one heavy quark and two lighter ones and it was clear that there should exist bullies with two heavy quarks. On this there was a complete consensus among the experts. The challenge was to predict from the theory the various properties of the trio that includes two heavy and one light." Prof. Karliner explains

An accurate prediction of the mass of the particle and an explanation of its name

"The most important characteristic of a bully is his arrogance." says Prof. Karliner. "In an article I wrote in 2014 together with Prof. Jonathan Rosner from the University of Chicago, who in his youth was a postdoctoral researcher with Prof. Yuval Naman here at Tel Aviv University. In the article we calculated all the possible combinations of two heavy quarks and one light quark, basically there are three options with undertones. There are two heavy quarks that come into consideration: c and b. The c quark is 1.5 times heavier than the proton, and the b is about 5 times heavier. The combination can be twice c, twice b or bc. The particle in question contains two c particles and one light quark particle - u. That is -ccu, a name that for historical reasons is denoted by the Greek letter xei, times the letter c because it has two C quarks, and two pluses because its electric charge is plus 2 and this is the meaning of its nickname ++Xi-cc.

"In the paper we predicted its mass and other properties that have not yet been measured. In the experimental results published today at a major conference of the European Physical Society dedicated to elementary particles, the scientists released the experimental result that they have been working on for almost a year in total secrecy. The bottom line is that the mass they measured is very close to the mass we predicted. The mass they measured was 3621 MEV (plus or minus one). For comparison, the mass of the proton is approximately 940, meaning the mass of the discovered particle is 3.5 times heavier than the proton. Our prediction from three years ago is 3627 plus or minus 12. The error in the prediction is less than 2 tenths of a percent of what was actually discovered. What makes the matter even nicer - that many before us and after us did the same calculation and published their results and they all missed big. Our prediction is the most accurate."

"The next thing I'm looking forward to is an experiment that will measure the half-life of the particle, that is, how long it takes for it to decay into a lighter particle. This figure also has a forecast in our research, and when it is measured we will know how accurate we were in this as well," Prof. Karliner concludes.

6 תגובות

  1. The top (what you call "top") does not appear in hadrons because its lifetime is very short. Before the quarks have enough time to connect to the structure, it has already decayed into lighter particles. Therefore in practice there are three heavy (and two light) quarks in this context.

  2. Three heavy quarks are mentioned in the article. I thought there were four - magical, strange, upper, lower. Who is left out and why?

  3. Not comparable to any breakthrough discovery. Important in itself for examining the existing theories (in particular QCD).

  4. Is the importance of the discovery (if completed) parallel in its importance to the discovery of the "Higgs"? It seems so, because it will deepen the knowledge and understanding about the strong nuclear power. Indeed an important achievement for Fr. Karliner and Fr. Rosner.

  5. I don't see the big breakthrough in perception, as it was in the last century Einstein, Heisenberg, Schrödinger, Feynman.
    Whole new fields of physics emerged. Another particle here and another micro discovery there.
    In mathematics, it is not with absolute certainty that a distinct senior mathematician is identified. In 2012 he published sinichi muzuchiki
    A new theory called inter-universal teichmuler theory. This is a mathematician who has already made breakthroughs in number theory in Abelian geometry in the past. After two years passed and no one understood the 500 pages within 4 articles he wrote, rumors spread that he was spouting nonsense. 5 years have passed and whoever is looking for information recently about the saturation of the articles, hears that there are 4 mathematicians in the western world who understand some of what he said and claim that these are not nonsense, and that he succeeds with the new insights he developed in number theory, to crack 100 open problems in mathematics, central, among them the ABC conjecture. (In the end it has a practical use in countless ways).
    2 main difficulties: a. He developed the theory over two decades, and it is a new language in mathematics - tools that did not exist before. It took people 5 years to start understanding the theory. B. The man is Japanese, he hardly ever leaves the borders of Japan, and he doesn't like to lecture too much. For his part, he types the articles, every time someone in the Revio team makes a comment that is not clear to me.
    He adds an explanation of how he came to the insight. It is estimated that a full understanding of the 4 articles will take about two decades. This is amazing. How something that a man invented, and four scientists of weight out of several dozen who performed a 5-year saturation think that it is not a joke, is difficult for the rest of humanity to understand.

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