| Issue |
EPJ Web Conf.
Volume 342, 2025
14th International Spring Seminar on Nuclear Physics “Cutting-Edge Developments in Nuclear Structure Physics”
|
|
|---|---|---|
| Article Number | 01030 | |
| Number of page(s) | 8 | |
| DOI | https://doi.org/10.1051/epjconf/202534201030 | |
| Published online | 21 November 2025 | |
https://doi.org/10.1051/epjconf/202534201030
Double Beta Decay of 48Ca within EMPM and STDA methods
1 Nuclear Physics Institute, Czech Academy of Sciences, 250 68 Řež, Czech Republic
2 Dipartimento di Matematica e Fisica, Università degli Studi della Campania “Luigi Vanvitelli,” viale Abramo Lincoln 5, I-81100 Caserta, Italy
3 Faculty of Mathematics and Physics, Charles University, 116 36 Prague, Czech Republic
4 Dipartimento di Fisica, Università di Napoli Federico II, 80126 Napoli, Italy
5 Faculty of Physics, Mathematics and Informatics Comenius University in Bratislava, Mlynská dolina F1, 842 48 Bratislava, Slovakia
6 Institute of Experimental and Applied Physics Czech Technical University in Prague, 110 00 Prague, Czech Republic
* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Published online: 21 November 2025
Abstract
The calculation of nuclear matrix elements (NMEs) for neutrinoless double-beta decay (0vßß) remains a major theoretical challenge in nuclear physics, as NMEs for this process cannot be accessed directly through experiment. Current nuclear structure models yield significantly different predictions for 0 vßß NMEs, making it essential to validate theoretical approaches using observables that are experimentally known. In contrast, two-neutrino double-beta decay (2vßß) has been measured in eleven isotopes, providing a valuable benchmark for testing the reliability of nuclear many-body methods.
In this work, we compute the 2vßß decay half-life of 48Ca using the Second Tamm-Dancoff Approximation (STDA) and the Equation of Motion Phonon Method (EMPM). By extending EMPM up to two-phonon configurations, we confirm that the two approaches yield practically identical numerical results, providing a strong internal consistency check. In addition, we study the dependence of the 2 vßß NME on the Gamow-Teller and Fermi contributions, on the particle-hole interaction strength parameter gph. Accurately reproducing the experimental 2 vßß half-life requires a substantial quenching of the axial-vector coupling constant gA. Furthermore, our theoretical framework outlines a strategy to mitigate this quenching issue by systematically including more complex configurations in the nuclear wave function.
© The Authors, published by EDP Sciences, 2025
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