蜜豆视频

Dr Arnoldas Deltuva, a scientist from the Institute of Theoretical Physics and Astronomy at 蜜豆视频 (VU) Faculty of Physics and master鈥檚 student Darius Likandrovas, in collaboration with an international team of colleagues, have advanced our understanding of the interactions between the particles that make up atomic nuclei 鈥� protons and neutrons. Their was published in 鈥淧hysical Review C鈥� under the prestigious Editor鈥檚 Suggestion category.

Typically, atomic nuclei possess not only a ground state 鈥� the lowest energy configuration 鈥� but also excited states, which have higher energies and exist only shortly before decaying. This enables scientists to probe the structure and interactions of the nucleus. 鈥淲e investigated the helium-4 nucleus, also known as the alpha particle. This nucleus is remarkable in that it has no bound excited states, even though its ground state exhibits an exceptionally large nucleon separation energy. We sought to understand why this is the case and what conditions govern the underlying processes, both in nature and in laboratory experiments. By theoretically modelling nuclear properties and comparing the results with experimental data, we revealed how universality connects the behaviour of the helium-4 nucleus with that of cold atoms and molecules 鈥� despite nuclear systems having energies a trillion times greater,鈥� explains Dr A. Deltuva, adding that solving such quantum physics problems could lead to unexpected applications in future technology development.

鈥淪implified models that allow us to isolate and examine a selected physical effect in more detail are also important for understanding the essence of physical processes,鈥� says young researcher D. Likandrovas. In his bachelor鈥檚 thesis, he explored how an increasing Coulomb interaction in a two-particle system transforms a bound state into a virtual or resonant one, thereby simulating the parametric evolution of the excited state of helium-4.

VU theoretical physicist Dr A. Deltuva emphasises that performing such calculations requires not only expertise in physics but also strong skills in mathematics and programming. 鈥淭he foundations for this line of research were laid about fifteen years ago. Currently, only a few research groups worldwide, including our team in Lithuania and colleagues in Belgium, Italy, and France, are capable of performing four-nucleon reaction calculations using a rigorous quantum framework. For this study, we joined forces with each group carrying out benchmark calculations using their own method,鈥� he explains. Dr Rimantas Lazauskas, an alumnus of the VU Faculty of Physics, who is continuing his scientific career at the University of Strasbourg in France, also contributed to this research.

Supercomputers are often used to perform calculations of nuclear processes, as accurate quantum mechanical modelling of nuclear reactions is an extremely large-scale task. 鈥淎 system of integral equations with many variables can be discretised and converted into an algebraic one, but if all its coefficients were written into a matrix, it would require up to a billion terabytes of data. We need to look for 鈥渟marter鈥� solution methods,鈥� says Dr A. Deltuva.

This time, VU scientists performed large-scale computer calculations using the resources and software of the Institute of Theoretical Physics and Astronomy. Their programs are the result of decades of work, paving the way for understanding the interactions and properties of the microscopic world, which is important for technological progress. Examples include the modelling of light nucleus fusion reactions, which are relevant to thermonuclear fusion, and simulations applied to the engineering of cold atom systems. To solve some of the tasks, scientists are developing neural network methods, working together with their colleague Dr Darius Jur膷iukonis, on a project funded by the Research Council of Lithuania, 鈥淩esearch in nuclear and particle physics using machine learning鈥� (No. S-CERN-24-2).

In the near future, the scientists plan to study even more exotic systems containing strange particles known as hyperons, as part of the recently approved project 鈥淭heoretical Modelling of Hypernuclear Reactions,鈥� funded by the Research Council of Lithuania.