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Münster (upm/ch).
Prof Michael Klasen (left) and Dr Tomáš Ježo from the Institute of Theoretical Physics stand between two bookshelves and look together at an open book that Tomáš Ježo is holding.<address>© Uni MS - Linus Peikenkamp</address>
Prof Michael Klasen (left) and Dr Tomáš Ježo from the Institute of Theoretical Physics are among the lead authors of the study.
© Uni MS - Linus Peikenkamp

Study shows influence of elementary particles on the structure of atomic nuclei

Researchers analyse binding of nucleons in atomic nuclei at the quark-gluon level for the first time / Bridge from nuclear to particle physics

In particle physics, quarks are known as the building blocks of nucleons – protons and neutrons – whose strong nuclear bonds are the product of gluons. How this force also indirectly holds nucleons together in atomic nuclei, however, is one of the most important questions in nuclear physics at present. Low-energy nuclear physics experiments have long demonstrated that the bound states of two nucleons play a special role in atomic nuclei. Now, a team from Europe and the USA led by Dr Tomáš Ježo and Prof Michael Klasen from the Institute of Theoretical Physics at the University of Münster has investigated these bound states at a higher resolution for the first time. To do this, they analysed particle physics data obtained at very high energies from the LHC particle accelerator at CERN in Geneva. These experiments are comparable to a microscopic examination. The higher the energy, the greater the resolution with which the nuclear building blocks can be analysed.

“To our surprise, despite the very different approaches, we found the same abundance of nucleon pairs as our colleagues had previously found at low energies,” says Tomáš Ježo. “Furthermore, we were able to show for the first time that quarks and gluons behave differently in these pairs than in free nucleons and also differently than previously expected in atomic nuclei. This has a decisive influence on our understanding of nuclear binding.” The study also shows that the abundance of pairs increases with nuclear mass and that proton-neutron pairs are particularly common.

Das Forschungsteam wertete unter anderem teilchenphysikalische Daten aus, die am Teilchenbeschleuniger LHC am CERN in Genf gewonnen werden.<address>© CERN - Samuel Joseph Hertzog</address>
Das Forschungsteam wertete unter anderem teilchenphysikalische Daten aus, die am Teilchenbeschleuniger LHC am CERN in Genf gewonnen werden.
© CERN - Samuel Joseph Hertzog
For the study, the “parton model of quantum chromodynamics”, which mathematically describes the interactions in atomic nuclei, played a key role. The research team expanded on the model by integrating individual nucleons and pairs of correlated nucleons into the analyses for the first time. The results have been published in the journal Physical Review Letters.

 

Funding

The research project was financed by the German Research Foundation (DFG).

Original publication

Denniston A. W., Ježo T. et al. (2024): Modification of Quark-Gluon Distributions in Nuclei by Correlated Nucleon Pairs. Physical Review Letters 133, 152502; DOI: 10.1103/PhysRevLett.133.152502

Further information