2026/07/27 by C. Brase, L. Jokiniemi, E. Kauppinen +4
#nucl-th #hep-ph #nucl-ex
We calculate the nuclear matrix elements and corresponding half-lives for the two-neutrino double-electron capture of 126Xe and the two-neutrino double-beta decay of 134Xe. We use different many-body methods: the proton-neutron quasiparticle random-phase approximation, the nuclear shell model, the microscopic interacting boson model, and an effective field theory for heavy nuclei. For both nuclei, all our half-life predictions are generally consistent with each other when including theoretical uncertainties for each method. Interestingly, for all calculations the lower range of the predicted 134Xe half-life is shorter than T2ν1/2 ≈ 2×1024 y, which may be within the reach of next-generation experiments. For 126Xe, our results typically predict one order of magnitude longer half-lives than those for 134Xe.