There’s no doubt that the Large Hadron Collider (LHC) is one of humanity’s greatest experiments, and thanks to recent upgrades, it’s working at such a high energy that a new mechanism of particle creation has become dominant.
According to scientists at the Institute of Nuclear Physics of the Polish Academy of Sciences, the collisions now produce two charmed mesons more often than they produce single charmed mesons due to the higher energy. Confused? We'll explain below.
“A few years ago, we predicted that collisions of protons at sufficiently high energy should result in more charm mesons produced in pairs rather than alone,” said Professor Antoni Szczurek in a statement. “Our latest publication not only describes in detail why this happens, but it also proves that in the LHC this effect is clearly visible.”
As the LHC smashes protons together, they move around its 27-kilometer (17-mile) ring at almost the speed of light. Collisions of high-energy protons lead to the formation of short-lived particles, some of which are these interesting charmed mesons.
Mesons are particles made of two quarks, the "building block" particles of the universe, while particles made of three particles like protons and neutrons are called hadrons. There are six types of quarks divided in light (up, down, strange) and heavy (charm, top, bottom); each of them has a corresponding anti-particle. Particles made of heavy quarks live for a very short time, so they can only be seen in particle accelerators.
During proton collisions, gluons (the carrier of the nuclear force that keeps atomic nuclei together) have enough energy to interact with each other and form particles like the so-called D0 mesons, which are made of one charm and one anti-up quark, and anti-D0 mesons. These are the charmed mesons that the LHC is producing.
“The data from the LHCb experiment have shown many cases where instead of one D0 meson we have two of them,” said Dr. Rafal Maciula, lead author of the study published in Physical Review B. “It is precisely the effect that we expected: production of twins is becoming as likely as the production of single mesons.”
Dr. Maciula added: “In future accelerators, such as the already designed Future Circular Collider, the LHC's successor, this phenomenon will play quite a dominant role in the production of charm particles. Perhaps then we will see collisions with a resulting effect of not only two, but three or more D mesons.”