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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BibTeX
@misc{xu2026beta,
title = {{Beta decay of potassium-54 reveals the role of two-body currents in neutron-rich nuclei}},
author = {Zhengyu Xu and Robert Grzywacz and Matthias Heinz and Thomas Papenbrock and Weijia Ong and James Allmond and Bertis Rasco and Krzysztof Rykaczewski and Hendrik Schatz and Bradley Sherrill and Oleg Tarasov and Peter Gysbers and Gaute Hagen and Petr Navratil and Samuel Ajayi and Honey Arora and Akaa Daniel Ayangeakaa and Hannah Berg and Jessica Berkman and Darren Bleuel and Konstantinos Bosmpotinis and Nico Braukman and Michael Carpenter and Giordano Cerizza and Aaron Chester and James Christie and Ian Cox and Heather L. Crawford and Benjamin Crider and Jacob Davis and Amelia Doetsch and Jeremias Garcia-Duarte and Alfredo Estrade and Aleksandra Fijalkowska and Christoforos Frantzis and Kei Fukushima and Tawfik Gaballah and Tim Gray and Erin Good and Kenny Haak and Shutaro Hanai and Jason Harke and Caley Harris and Adam Hartley and Marc Hausmann and Kirby Hermansen and Daniel Hoff and Donnie Hoskins III and James Huffman and Rahul Jain and Marek Karny and Thomas King and Noritaka Kitamura and Kay Kolos and Elaine Kwan and Sean Liddick and Brenden Longfellow and Rebeka Lubna and Stephanie Lyons and Miguel Madurga},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36218},
eprint = {2610.36218},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36218},
}
RIS
TY - UNPB
TI - Beta decay of potassium-54 reveals the role of two-body currents in neutron-rich nuclei
AU - Zhengyu Xu
AU - Robert Grzywacz
AU - Matthias Heinz
AU - Thomas Papenbrock
AU - Weijia Ong
AU - James Allmond
AU - Bertis Rasco
AU - Krzysztof Rykaczewski
AU - Hendrik Schatz
AU - Bradley Sherrill
AU - Oleg Tarasov
AU - Peter Gysbers
AU - Gaute Hagen
AU - Petr Navratil
AU - Samuel Ajayi
AU - Honey Arora
AU - Akaa Daniel Ayangeakaa
AU - Hannah Berg
AU - Jessica Berkman
AU - Darren Bleuel
AU - Konstantinos Bosmpotinis
AU - Nico Braukman
AU - Michael Carpenter
AU - Giordano Cerizza
AU - Aaron Chester
AU - James Christie
AU - Ian Cox
AU - Heather L. Crawford
AU - Benjamin Crider
AU - Jacob Davis
AU - Amelia Doetsch
AU - Jeremias Garcia-Duarte
AU - Alfredo Estrade
AU - Aleksandra Fijalkowska
AU - Christoforos Frantzis
AU - Kei Fukushima
AU - Tawfik Gaballah
AU - Tim Gray
AU - Erin Good
AU - Kenny Haak
AU - Shutaro Hanai
AU - Jason Harke
AU - Caley Harris
AU - Adam Hartley
AU - Marc Hausmann
AU - Kirby Hermansen
AU - Daniel Hoff
AU - Donnie Hoskins III
AU - James Huffman
AU - Rahul Jain
AU - Marek Karny
AU - Thomas King
AU - Noritaka Kitamura
AU - Kay Kolos
AU - Elaine Kwan
AU - Sean Liddick
AU - Brenden Longfellow
AU - Rebeka Lubna
AU - Stephanie Lyons
AU - Miguel Madurga
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.36218
UR - https://arxiv.org/abs/2610.36218
AB - 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.
ER -