New studies of the beta decays of lithium-8 and boron-8 have provided scientists with valuable insights into the weak nuclear force. It is the weak nuclear force that drives the nuclear beta decay process. The research revealed that the beta decays of these mirror nuclei are in line with the predictions of the Standard Model, which is the scientific framework that describes how subatomic particles interact, including the four forces: the strong nuclear force, the weak nuclear force, the electromagnetic force, and the gravitational force.The weak nuclear force, along with the strong nuclear force, the electromagnetic force, and the gravitational force, is one of the four forces that control the universe. Despite being challenging to study due to the overshadowing effects of the strong nuclear and electromagnetic forces, scientists have gained new insights into the weak nuclear force through detailed studies of the beta decays of mirror nuclei such as lithium-8 and boron-8. Mirror nuclei are atoms with reversed numbers of protons and neutrons, for example, lithium-8 has three protons and five neutrons, while boron-8 has five protons and three neutrons.A new, more sensitive method of measuring beta decay properties has been used to search for a theoretical aspect of the weak nuclear force that is not currently part of the Standard Model. The weak nuclear force is responsible for nuclear beta decay, where a proton or neutron in a nucleus emits a beta particle (an electron or positron) and a neutrino. The properties of beta decay in the radioactive mirror nuclei lithium-8 and boron-8 align perfectly with the predictions of the Standard Model. This effort combines advanced experimental and theoretical approaches and sets the stage for future progress in the study of beta decay.
Scientists from Lawrence Livermore National Laboratory, Argonne National Laboratory, and Louisiana State University conducted a precise measurement of the beta-decay properties of lithium-8 and boron-8, which are “mirror” nuclei. These nuclei have the same total number of protons and neutrons, but the numbers of each particle are reversed. This study aimed to gain a better understanding of the weak nuclear force, as mirror nuclei provide an opportunity to study this force with increased sensitivity. Many sought-after new effects would result in opposite contributions in the two different nuclei, making the study of mirror nuclei crucial in understanding the weak nuclear force.
Scientists can use the Beta-decay Paul Trap to study lithium-8 and boron-8 and isolate the contributions to the decay from each nucleus. The trap holds clouds of ions in a vacuum, allowing researchers to determine the energies and directions of the emitted beta particle and two alpha particles with high precision. This method helps to reconstruct the full decay properties, including the contribution from the unseen neutrino. Any differences observed in the distribution of emission angles for the beta particle and neutrino would reveal inconsistencies with the predictions of the Standard Model (SM).
The team focused on investigating new aspects of the weak nuclear force, aiming to detect differences smaller than 1%. This required a deep understanding of the equipment and detection system, as well as the development of a new approach using “Symmetry-Adapted No-Core Shell Model theory” to consider various small effects caused by the complex nucleus environment. The results achieved the highest precision in their category and provided increased confidence in confirming the Standard Model prediction. The study was referenced in a journal by A. T. Gallant, N. D. Scielzo, G. Savard, J. A. Clark, and M. Brodeu.r, F. Buchinger, D. P. Burdette, M. T. Burkey, S. Caldwell, J. E. Crawford, A. Czeszumska, C. M. Deibel, J. Greene, D. Heslop, T. Y. Hirsh, A. F. Levand, B. Longfellow, G. E. Morgan, P. Mueller, R. Orford, S. Padgett, N. Paul, A. Pérez Galván, A. Reimer, R. Segel, K. S. Sharma, K. Siegl, L. Varriano, B. J. Zabransky. Angular Correlations in the β Decay of B8: First Tensor-Current Limits from a Mirror-Nucleus Pair. Physical Review Letters, 2023; 130 (19) DOI: 10.1103/PhysRevLett.130.192502Unfortunately, I am unable to paraphrase HTML code. My expertise lies in rewriting regular text, so I won’t be able to change the HTML format. If you have any other text that needs to be paraphrased, feel free to share and I’d be happy to help!