A historical event took place in nuclear physics – the international group of scientists managed to recreate all the observed properties of atomic nuclei using only quarks and gluons. This breakthrough has significant implications for the field of science.
Almost a century ago, physicists discovered that the atomic nucleus consists of protons and neutrons. Initially, these particles were thought to be indivisible, but in the 1960s, a hypothesis emerged suggesting that at high energies, they reveal their internal structure – quarks held together by gluons.
Despite experimental confirmation of the existence of quarks, reproducing the results of nuclear experiments with low energies, where only protons and neutrons are visible in atomic nuclei, proved challenging for many decades.
Dr. Alexander Kusina, a theorist from the Institute of Nuclear Physics of the Polish Academy of Sciences involved in the study, explained that until now, there were two separate descriptions of atomic nuclei – one for low energies based on protons and neutrons, and the other for high energies based on quarks and gluons.
Physicists typically study atomic nuclei by bombarding them with smaller particles, often electrons. At low energies, the nuclei behave as composites of nucleons, while at high energies, partons such as quarks and gluons become visible inside them.
In their research, scientists utilized data from high-energy collisions, including those from the Large Hadron Collider at CERN in Geneva. The primary objective was to examine the partial structure of atomic nuclei at high energies using Parton Distribution Functions (PDFs).
The study significantly expanded the understanding of PDFs. Drawing inspiration from nuclear models describing low-energy collisions, where protons and neutrons form strongly interacting pairs, scientists were able to determine the PDFs for 18 different atomic nuclei, including their position in correlated nucleon pairs.
The results reaffirmed findings from low-energy experiments, showing that the majority of correlated pairs consist of proton-neutron pairs, a particularly fascinating result for heavy nuclei like gold or lead.
Dr. Kusina highlighted that the improved modeling of nucleon pairing simplifies the theoretical description, enabling more precise studies of partner distributions in individual atomic nuclei in the future.
These new findings pave the way for a deeper understanding of atomic nucleus structure, consolidating both high-energy and low-energy aspects into a unified framework.