arXiv · 2610.36218
Beta decay of potassium-54 reveals the role of two-body currents in neutron-rich nuclei
Abstract
The beta decay of neutron-rich nuclei probes the microscopic nature of weak interactions in the nuclear medium under extreme conditions. Such weak decays drive the synthesis of heavy elements in astrophysical environments, but remain poorly understood. Far from stability, experimental data are scarce, placing strong demands on ab initio nuclear theory. Two-body weak currents have been proposed as the dominant mechanism responsible for the universal quenching of theoretically predicted Gamow-Teller decay strength. However, direct experimental validation in neutron-rich nuclei has been lacking. Here we measure the beta decay of 54K, a nucleus at the experimental frontier of radioactive ion-beam facilities. In this work, the doubly magic nature of the daughter nucleus 54Ca results in a remarkably simple decay pattern, dominated by a single transition to a neutron-unbound state at 6.2 MeV with a comparative partial half-life logft=4.4(1) or Gamow-Teller decay strength B(GT)=0.26 (+0.08) (-0.04). Our measurement is reproduced by new state-of-the-art calculations of the decay, providing direct evidence for the essential role of two-body currents in nuclear beta decay for systems with a significant neutron excess. We establish a key benchmark for theoretical predictions of weak processes in exotic nuclei.
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Zhengyu Xu, Robert Grzywacz, Matthias Heinz, Thomas Papenbrock, Weijia Ong, James Allmond, Bertis Rasco, Krzysztof Rykaczewski, Hendrik Schatz, Bradley Sherrill, Oleg Tarasov, Peter Gysbers, Gaute Hagen, Petr Navratil, Samuel Ajayi, Honey Arora, Akaa Daniel Ayangeakaa, Hannah Berg, Jessica Berkman, Darren Bleuel, Konstantinos Bosmpotinis, Nico Braukman, Michael Carpenter, Giordano Cerizza, Aaron Chester, James Christie, Ian Cox, Heather L. Crawford, Benjamin Crider, Jacob Davis, Amelia Doetsch, Jeremias Garcia-Duarte, Alfredo Estrade, Aleksandra Fijalkowska, Christoforos Frantzis, Kei Fukushima, Tawfik Gaballah, Tim Gray, Erin Good, Kenny Haak, Shutaro Hanai, Jason Harke, Caley Harris, Adam Hartley, Marc Hausmann, Kirby Hermansen, Daniel Hoff, Donnie Hoskins III, James Huffman, Rahul Jain, Marek Karny, Thomas King, Noritaka Kitamura, Kay Kolos, Elaine Kwan, Sean Liddick, Brenden Longfellow, Rebeka Lubna, Stephanie Lyons, Miguel Madurga, Mejdi Mogannam, Shree Neupane, Timilehin Ogunbeku, Gerard Owens-Fryar, Jayden Palomino, Mauricio Portillo, Mustafa Rajabali, Andrea Richard, Isaiah Richardson, Eleanor Ronning, Gregory Rose, Thomas Ruland, Nicholas Scielzo, Dustin Scriven, Darek Seweryniak, Kevin Siegl, Mallory Smith, Artemis Spyrou, Michał Stepaniuk, Adriana Sweet, Vandana Tripathi, Artemis Tsantiri, Sivahami Uthayakumaar, William Walters, Shane Watters, Marzena Wolinska-Cichocka, Rin Yokoyama. 2026-10-26. Beta decay of potassium-54 reveals the role of two-body currents in neutron-rich nuclei. https://arxiv.org/abs/2610.36218
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