Physicists sifting data from older particle accelerators have found evidence of a very elusive, never-before-seen process, the so-called triangular peculiarity.
The triangular singularity, first conceived by Russian physicist Lev Landau in the 1950s, refers to a rare elementary particle process in which particles exchange identities before they separate from each other. In this scenario, two particles called kaons form the two corners of the triangle, and the particles they exchange form the third point of the triangle.
“The particles contained exchanged quarks and changed their identities in the process,” said Bernhard Kettzer, a research co-author at the Helmholtz Institute for Radiation Nuclear Physics at the University of Bonn. Said in a statement..
And it is called a singularity because the mathematical method for describing the interaction of subatomic particles collapses.
If this very strange particle identity exchange actually happens, it’s a physicist Strong force, Join the nuclei.
Point to the compass
In 2015, a physicist studying particle collisions at CERN in Switzerland thought he had a quick glimpse of a collection of short-lived exotic particles known as tetraquarks. But new research supports another interpretation — even stranger. Instead of forming a new group, the pair of particles exchanged identities before flying. This exchange of identities is known as the singularity of the triangle, and this experiment may have unexpectedly provided the first evidence of the process.
The COMPASS (Common Muon and Proton Device for Structure and Spectroscopy) experiment at CERN studies strong forces. The work of force is very simple (keeping protons and neutrons glued together), but the force itself is fast-paced and complex, and physicists have had a hard time fully explaining its behavior in all interactions.
Therefore, in order to understand the strong force, COMPASS scientists crush particles with ultra-high energy in an accelerator called the Super Proton Synchrotron. Then they are watching what happens.
They start with a pion, which consists of two basic components, quarks and antiquarks. The strong force keeps the quarks and antiquarks glued inside the pion.Unlike others The basic power of nature, The weaker with distance, the stronger the force as the quarks move away (imagine a pion quark attached with a rubber band; the more you pull it apart, the stronger it becomes).
Scientists then accelerate the pion to near the speed of light and hit it Hydrogen atom.. The collision breaks the strong force bond between the quarks and releases all of its stored energy. “This is converted into matter, creating new particles,” Ketzer said. “Therefore, such experiments provide us with important information about strong interactions.”
4 quarks or triangles?
In 2015, COMPASS analyzed a record 50 million such collisions and found an interesting signal. In the aftermath of these collisions, the time for new particles to emerge was less than 1%. They dubbed the particle “a1 (1420)” and initially thought it was a new group of four quarks, the tetraquark. However, the Tetraquark was so unstable that it collapsed into something else.
Related: Seven strange facts about quarks
This was a big problem because quarks are usually provided in three groups (which make up protons and neutrons) or pairs (such as pions). The group of four quarks was certainly a rare discovery.
But a new analysis published in the journal in August Physical review letter, Provides an even stranger interpretation.
Instead of easily creating a new tetraquark, all these pion collisions created something unexpected. It is the singularity of the legendary triangle.
Here comes the triangle
This is what the researchers behind the new analysis think is happening. The pion crashes into a hydrogen atom and collapses, and all the strong energy of force creates a flood of new particles. Some of those particles are kaons, which are yet another kind of quark-antiquark pair. Very rarely, when two kaons are generated, they start moving in different ways. Eventually, these kaons decay into other, more stable particles. But before doing so, they exchange one of the quarks with each other and transform themselves in the process.
It is the short exchange of quarks between two kaons that mimics the tetraquark signal.
“Particles contained exchanged quarks and changed their identities in the process,” said Kettzer, who is also a member of the interdisciplinary research area “Building Blocks of Matter and Fundamental Interactions” (TRA Matter). .. “The resulting signal looks exactly like the signal from Tetraquark.”
When graphing the path of individual particles after the first collision, a pair of kaons form two legs, the exchanged particles form a third between them, and a triangle appears in the figure. Therefore, it is given this name.
Physicists have predicted triangular singularities for more than half a century, and this is the closest thing to actually observing triangular singularities in any experiment. But it’s not yet a slam dunk. The new model of the process containing the singularities of the triangle has fewer parameters than the tetraquark model and is better suited for the data. However, it is not definitive, as the original Tetraquark model can still explain the data.
Still, it’s an interesting idea. If it holds up, it will be a powerful investigation of strong nuclear forces. Because the appearance of the singularity of the triangle is a prediction of our understanding of its power, which has not yet been fully examined.
Originally published in Live Science.
The first signs of an elusive “triangular singularity” indicate that particles are exchanging identities during flight.
Source link The first signs of an elusive “triangular singularity” indicate that particles are exchanging identities during flight.