A groundbreaking approach to studying atomic nuclei and their internal components has been developed by scientists. The method relies on modeling the production of specific particles resulting from high-energy collisions between electrons and nuclear targets, a process set to occur at the Electron Ion Collider (EIC) in the future. The research, published in Physical Review Letters, highlights that collisions exclusively producing single mesons can offer insights into the large-scale structure of the nucleus, unveiling details about its size and shape, whether it resembles a cigar or a pancake. Higher-momentum mesons, produced at the EIC, can reveal nuclear structure at shorter length scales, providing information about the arrangement of quarks and gluons within protons and neutrons.
Unlike traditional methods, such as colliding two nuclei at relatively low energy or exciting nuclei in an electromagnetic field, this new approach focuses on studying mesons exclusively produced in EIC collisions. Traditional methods mainly provide information about the distribution of electric charge within nuclei, while the new method offers a deeper understanding of the distribution of gluons—the particles binding the quarks that make up nuclear building blocks. Described as a form of “X-ray vision” for atoms, this innovative technique, developed by theorists from Brookhaven National Laboratory, the University of Jyvaskyla in Finland, and Wayne State University, establishes a theoretical framework for studying nuclear structure at the future EIC.
The research emphasizes that EIC collisions producing single vector mesons can offer sensitivity to the detailed structure of the nuclear target. In these collisions, the target may either remain intact or break up. When the target breaks up, the cross-section, measuring the probability of the process occurring, becomes sensitive to fluctuations in the target, driven by position fluctuations of neutrons and protons. The study shows that when the target is deformed, these fluctuations undergo significant modifications, altering the measured cross-section. As these measurements are conducted at much higher collision energy than traditional experiments, they become sensitive to the gluon distributions inside the protons and neutrons of the nucleus.
Measuring gluon distributions, instead of the distribution of electric charge, promises new insights into the differences between these two distributions and how the gluon distribution depends on the energy used for measurement. This pioneering technique charts a new course for research at the EIC, potentially providing crucial information complementing traditional nuclear structure experiments. It holds the potential to unravel how nuclear shapes evolve with energy and deliver previously inaccessible details about nuclear structure.
Source: Brookhaven National Laboratory