(ORDO NEWS) — By colliding particles at the Large Hadron Collider, scientists have found evidence of an exotic X(3872) meson that does not fit into the existing quark model.
Its study will help to better understand the processes that took place in the first moments of the existence of the Universe.
Before forming the stable particles—protons and neutrons we are accustomed to—millionths of a second after the Big Bang, the matter in our universe was a very hot quark-gluon plasma. In it, elementary particles collided, creating short-lived combinations.
One of them is the so-called X particle, which does not fit into the quark model due to unusual quantum numbers. In a new study, scientists have shown for the first time that ” X particles ” can be formed by collisions of relativistic heavy ions, namely lead ions.
For the first time, physicists observed the “X particle” in 2003 as part of an experiment on the collision of high-energy electrons and positrons.
But then the lifetime of the particles was not enough to study their structure in detail. So the scientists suggested that the “X particle” could be recreated and studied more closely in a quark-gluon plasma.
In the new study, measurements were taken on one of the two particle detectors at the Large Hadron Collider, the Compact Muon Solenoid ( CMS) . The CMS collaboration includes physicists from dozens of countries, including specialists from Russia.
Machine learning techniques were used to process data from more than 13 billion lead ion collisions, each producing tens of thousands of particles.
The algorithm was taught to identify decay patterns characteristic of “particles X”: the fact is that after a short time after formation, particles scatter into their constituent parts, and the pattern of this decay is unique for “particles X”.
Thanks to this approach, it was possible to isolate about 100 “X particles” – or exotic X (3872) mesons, so named because of their calculated mass.
So far, scientists don’t know exactly what X(3872) is made of: it’s either a compact tetraquark, or a completely new type of particle, consisting of two weakly bound mesons, which themselves are composed of two quarks.
Now that the scientists have found a way to produce enough of these exotic mesons, they plan to study the internal structure of the “X particle”. This can change the existing idea about the structure of matter in the Universe.
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