The study of the structure of the atomic nucleus and strong nuclear interaction was the first step towards a deeper understanding of matter: from protons and neutrons to quarks, towards the Standard Model of particle physics.
The Frascati National Laboratories have always played a key role in this research field, implementing experiments on site or at other international laboratories, at the frontier of physics knowledge for a deeper understanding of fundamental interactions in the field of nuclear physics and their role in the Universe, from the Big Bang to the present day.
Strong interaction, one of the four fundamental interactions in the Universe, is described by quantum chromodynamics (QCD). Many aspects of QCD, especially at low energies, remain unclear due to the lack of experimental data.
In the very first instants of the creation of the Universe, in times of less than ten-thousandths of a second, all matter was in a plasma state consisting of quarks and gluons, the fundamental building blocks of matter. At the CERN LHC accelerator in Geneva, the largest particle collider ever built, the ALICE (A Large Ion Collider Experiment) experiment is dedicated to investigating this type of matter produced by making lead ions collide at very high energy.
The GRAAL experiment, at the ESRF Laboratory in Grenoble, has concentrated its efforts in the study of the excited states of the nucleon in order to obtain information on the cohesive force between its constituent quarks.
Atomic nuclei consist of neutrons and protons (nucleons), which are not elementary particles but consist of quarks and gluons. The interaction between quarks and gluons is accurately described by Quantum Chromodynamics. However, the way in which these elementary particles bind to form nucleons is still not explainable in an entirely satisfactory manner.
One of the fundamental principles of quantum mechanics and modern physics is the Pauli Exclusion Principle (PEP). The most direct consequence is the structure of atoms: the way in which electrons fill the different atomic layers around the nucleus. Without this principle, matter would not exist in the known form.