Flavor symmetry in the high energy world does not work as expected

In the collision between argon and scandium nuclei, scientists from the International NA61/Shine experiment observed a distinct anomaly indicating a violation of approximate flavour symmetry between the up and down Quarks, one of the most important symmetry in the quark world.

The presence of anomalies may be due to previously unknown inadequacies in current nuclear collision models, but it cannot rule out potential connections to long-term “new physics.”

If the structure is assembled using the same number of wooden and plastic blocks, it is expected that the proportion between the two types of blocks will not be changed after being dismantled. Physicists have so far lived in the belief that similar symmetry in the early and final states, known as flavor symmetry, occurs in collisions between particles containing upper and lower quarks.

However, another photograph of reality comes from a paper published in Nature Communications.

An interesting observation with very continuous results was made by the NA61/Shine Experiment Group. The key part of this includes Polish physicists and researchers at the Institute of Nuclear Physics (IFJ PAN) at the Polish Academy of Sciences in Krakow.

The team studied collisions between argon and scandium nuclei accelerated by superproton synchrotrons (SPS). This is the same accelerator that is also involved in the final stage of accelerating the protons before injecting into a large hadron collider (LHC) at CERN near Geneva.

“According to the current state of knowledge, the world of matter we perceive is primarily composed of basic particles called Quarks, each having an antimatter counterpart. The basic components of the atomic nucleus, the protons and neutrons, are made up of evays-mixed and down-quark triplets. Explain.

The factors that adhesion of quarks to protons, neutrons, or mesons are powerful interactions described by a theory called quantum chromodynamics. From that equation, if all types of quarks had the same mass, a strong interaction would not distinguish between any of them. In fact, the mass of the quark (flavors) of various varieties is very different, destroying this symmetry.

But what is very important is that the two lightest types of quarks (the aforementioned up and down Quarks) are almost certain to the masses. Thus, powerful interactions are sufficient to talk about the existence of approximate flavor symmetry, rather than treating them in the exact same way.

In nuclear research, the importance of this symmetry is important. If a high-energy collision containing an up-quark produces several secondary particles with a certain probability, then with roughly the same probability, other corresponding secondary particles are generated in collisions where down-quarks are present (and vice versa).

The NA61/Shine Experiment team was involved in the study of K Mesons (Kaons), which appear in various types during high-energy collisions of Argon and Scandium nuclei. Originally, the group had planned to measure only electrically charged kones. It was also known that short-lived neutral chaons without charge were produced in collisions, but measuring them seemed worthless.

After all, the symmetry of the flavor revealed that if negative and positive cons were added, the results should correspond to the number of neutral cones to a good approximation. However, in the end, the group decided to perform measurements of all types of kons, which was a huge success.

“The results published by our team have been found to be statistically significantly different from previous theoretical predictions. As this energy range usually does not exceed 3%, it is assumed that the discrepancy in experimental data will not exceed 3% over this energy range.

Looking closer, the observed effects become even more interesting. The stable isotopes of argon have 18 protons and 22 neutrons, while in the case of scandium there are three neutrons in the nucleus, which are more stable than the protons.

Because the protons are two up-quark and one down-quark conglomerates, and neutrons are the opposite, simple arithmetic proves that there is a slight down-quark in the system investigated before the collision.

“We started with more down quarks than up quarks, so if there is a breakdown of flavor symmetry, we intuitively expect that we need to observe more down quarks after collision. Our analysis is clearly shown. Flavor symmetry is, in other directions, at the end, up quarks of sed of semad of ablars ot new one op of semad of ablarks or ablarks is Katarzyna Grebieszkow of the Institute of Technology of Warsaw.

The reason for the symmetric destruction observed in collisions between the Argon and the Scandium nucleus is currently unknown.

Perhaps theoretical calculations inspired by quantum chromodynamics do not take into account some of the important properties of these collisions. But we cannot rule out another grander possibility. The observed effect is that it surpasses existing theories of powerful interactions and standard models built on them. In other words, it means that it is a manifestation of a long-term “new physics.”

Regardless of further development, this discovery has great implications for scientists already involved in studying high-energy collisions between particles and nuclei. In fact, the assumption of the existence of symmetry in question has been widely used for decades in modeling courses of many nuclear testing and interpreting their results.

“The point is that the flavour symmetry of collisions between nuclei has been discovered. Today, it is not yet possible to say whether this is a universal phenomenon that affects all interactions with the existence of quarks, or whether it only occurs with a specific mass of nuclei, or other collisions.”

“In practice, this implies a need for a careful reevaluation of almost every model of particle production in high-energy collisions, and virtually every model of numerous experimental results.”

In the coming months, scientists on the NA61/SHINE team will begin work to see the flavour symmetry breaking of collisions, featuring the same number of up and down Quarks.

“The initial focus lies in millions of already recorded collisions of Pi+ and Pimesons with carbon nuclei, where we can talk about the perfect flavor symmetry before the collision,” says Dr. Seweryn Kowalski, professor at Silesia University.

“The next step is to study the course of oxygen oxygen and magnesium-magnesium collisions. The latter system appears to be particularly promising due to the similar nuclei complexity as argon and scandium.

Researchers say we still need to wait for the most interesting results. Magnesium nuclear collisions are only possible after a three-year upgrade of the LHC.