We present the results of our calculation of the nuclear matrix element for the \ (2 \) decay \ (^48 Ca ^{48 Ti}\), performed using a post-Hartree–Fock (HF) Density Functional Theory-based No-Core Configuration-Interaction (DFT-NCCI) framework developed by our group. The preliminary value we have obtained for the nuclear matrix element describing this process, \ (| M^2 | = 0. 056 (6) \) MeV\ (^-1\), is in excellent agreement with the results of the shell-model study by Horoi et al. , which yielded 0. 054 (0. 064) MeV\ (^-1\) for the GXPF1A (GXPF1) interactions, respectively. It is also in reasonable agreement with the most recent experimental estimate from the review by Barabash, which is 0. 068 (6) MeV\ (^-1\), assuming a quenching factor \ (qg ₀ 1\). The consistency of our prediction with the shell-model results strengthens our confidence in the nuclear modeling of this second-order, extremely rare process, which is of paramount importance for the further modeling of the \ (0 \) decay. Abstract Published by the Jagiellonian University 2026 authors
Miśkiewicz et al. (Tue,) studied this question.