The first image of an atomic nucleus ⚛️ containing quarks and gluons

Atomic nuclei, composed of protons and neutrons, hide quarks and gluons at their heart. The latter, still difficult to study, have long eluded scientists.

In the mid-20th century, physicists discovered that protons and neutrons are the main components of atomic nuclei. But a new revelation changed everything: these particles are made up of quarks.

In the 1960s, researchers understood that quarks interact using gluons. This model, revolutionary at the time, nevertheless remained incomplete in explaining certain low-energy phenomena. Scientists faced an impasse: how to unify the behavior of low-energy protons and neutrons and that of high-energy quarks and gluons? The enigma persisted until recently. Physicists, notably those from the Institute of Nuclear Physics in Krakow, have developed a model combining data from high and low energy collisions. This model finally explores this border.

Thanks to experiments carried out at CERN’s LHC, they analyzed atomic nuclei at high energy, revealing the internal distribution of quarks and gluons. This advance allows a more detailed understanding of nuclear interactions. The research focused on eighteen atomic nuclei, ranging from carbone to gold. The results confirmed that most nucleon pairs consist of a proton and a neutronespecially in heavy nuclei.

The perspectives offered by these discoveries could revolutionize nuclear physics and open the way to new experiments to unlock the secrets of matter.

What is a quark?

A quark is a elementary particle which constitutes the protons and neutrons within the atomic nucleus. There are six types (called “flavors”): up, down, charm, strange, top and bottom. Quarks interact strongly with each other thanks to gluons, particles which transmit nuclear force strong, one of the fundamental forces of physics.

Quarks are held together by gluons, which act like invisible “glues.” These gluons exert the strong nuclear force, the most powerful of the fundamental forces, and help maintain the quarks inside the protons and neutrons. It’s this interaction which ensures the stability of atomic nuclei.

The quark-gluon model is a theoretical description that explains the internal structure of protons and neutrons. At high energies, this approach is used to study how quarks and gluons are distributed inside subatomic particles, and how they behave during energetic collisions, such as those carried out in particle accelerators.