2025/06/16 by Jan Miśkiewicz, Miśkiewicz, Jan, M. Konieczka +3
Physics and Astronomy · #FOS: Physical sciences #Neutrino Physics Research #Nuclear Theory (nucl-th) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2506.13747
openalex publication_date 2025/06/16 · openalex created_date 2025/10/13 · openalex updated_date 2026/07/28
We present a seminal calculation of the nuclear matrix element for the two-neutrino double beta (2νββ) decay of 48Ca → 48Ti using a post-Hartree-Fock (HF) Density Functional Theory-based No-Core Configuration-Interaction (DFT-NCCI) framework developed by our group [Phys. Rev. C 94, 024306 (2016)]. In the present calculation, we utilize a variant of the approach that restores rotational symmetry and mixes states projected from self-consistent mean-field configurations obtained by solving the HF equations with the density-independent local Skyrme interaction. Our calculations yield |M2νββ| = 0.056(6) MeV-1 for the nuclear matrix element describing this process. This result is in very good agreement with shell-model studies - for example, with the calculations by Horoi \it et al.\/ [Phys. Rev. C 75, 034303 (2007)], which yielded 0.054 (0.064) MeV-1 for the GXPF1A (GXPF1) interactions, respectively. It is also in a reasonable agreement with the most recent experimental estimate from the review by Barabash, which is 0.068(6) MeV-1, assuming quenching qgA ≈ 1. The consistency of our prediction with the shell-model results increases our confidence in the nuclear modeling of this second-order, very rare process which is of paramount importance for further modeling of the neutrinoless double beta (0νββ) decay process.