Application of an efficient generator-coordinate subspace-selection algorithm to neutrinoless double-
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 decay

Romero, A. M.; Yao, J. M.; Bally, B.; Rodrı́guez, T.; Engel, J.

doi:10.1103/physrevc.104.054317

Cited by 14 publications

(11 citation statements)

References 28 publications

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“…8 -complemented by a M 0ν short NME which enhances M 0ν light by about 40% (Wirth et al, 2021). Strategies to study heavier ββ emitters are in progress (Romero et al, 2021).…”

Section: Ab Initio Methodsmentioning

confidence: 99%

Toward the discovery of matter creation with neutrinoless double-beta decay

Agostini¹,

Benato²,

Detwiler³

et al. 2022

Preprint

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The discovery of neutrinoless double-beta decay could soon be within reach. This hypothetical ultra-rare nuclear decay is a portal to new physics beyond the Standard Model. Its observation would constitute the discovery of a matter-creating process, corroborating leading theories of why the universe contains more matter than antimatter, and how the forces unify at high energy scales. It would also prove that neutrinos and antineutrinos are not two distinct particles, but can transform into each other, generating their own mass in the process. The recognition that neutrinos are not massless necessitates an explanation and has boosted interest in neutrinoless double-beta decay. The field is now at a turning point. A new round of experiments is currently being prepared for the next decade to cover an important region of parameter space. Advancements in nuclear theory are laying the groundwork to connect the nuclear decay with the underlying new physics. Meanwhile, the particle theory landscape continues to find new motivations for neutrinos to be their own antiparticle. This review brings together the experimental, nuclear theory, and particle theory aspects connected to neutrinoless double-beta decay, to explore the path toward -and beyond -its discovery.

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“…8 -complemented by a M 0ν short NME which enhances M 0ν light by about 40% (Wirth et al, 2021). Strategies to study heavier ββ emitters are in progress (Romero et al, 2021).…”

Section: Ab Initio Methodsmentioning

confidence: 99%

Toward the discovery of matter creation with neutrinoless double-beta decay

Agostini¹,

Benato²,

Detwiler³

et al. 2022

Preprint

View full text Add to dashboard Cite

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“…is smaller than a pre-selected cutoff parameter L c [31]. This implies that the new configuration is approximately orthogonal to the previous configurations, hence the name of this stage.…”

Section: Illustrationsmentioning

confidence: 99%

“…The latter are vital for interpreting and planning the current-and next-generation tonne-scale experiments for 0νββ decays (see the recent reviews [28][29][30]). GCM calculations most frequently use modern energy density functionals (EDFs) and effective Hamiltonians as inputs, but there have been several works that employ nuclear forces from chiral Effective Field Theory (EFT) in recent years, as the GCM has attracted interest as an pathway for extending nuclear ab initio calculations to deformed nuclei [26,27,[31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

“…In applications, one often observes that many of the basis functions connected by the generator coordinates have little contribution to the wave functions of low-lying states and can therefore be safely omitted -see, for instance, Refs. [31,38,39]. In other words, a careful selection of the basis functions can reduce the dimensions of the GEE, and therefore the computational cost.…”

Section: Introductionmentioning

confidence: 99%

“…These parameters of EC are analogous to the generator coordinates in GCM, hence finding an efficient way for sampling the basis functions that define a subspace to represent the states of interest is important for both EC and GCM [38]. Several algorithms have been proposed, including the variationafter-projection algorithm [47][48][49], the stochastic sampling with Monte-Carlo techniques [50][51][52], the choice of lowlying quasiparticle Tamm-Dancoff modes [53], the energytransition-orthogonality procedure (ENTROP) [31], and the discrete nonorthogonal shell model (DNO-SM) [54]. We note that many of these algorithms still require a substantial computational effort for the subspace determination.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of generator coordinate method with machine-learning techniques for nuclear spectra and neutrinoless double-beta decay: ridge regression for nuclei with axial deformation

Zhang¹,

Lin²,

M.³

et al. 2022

Preprint

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Background: The generator coordinate method (GCM) is an important tool of choice for modeling large-amplitude collective motion in atomic nuclei. Recently, it has attracted increasing interest as it can be exploited to extend ab initio methods to the description of collective excitations of medium-mass and heavy deformed nuclei, as well as the nuclear matrix elements (NME) of candidates for neutrinoless double-beta (0νββ) decay.Purpose: The computational complexity of the GCM increases rapidly with the number of collective coordinates. It imposes a strong restriction on the applicability of the method. We aim to exploit machine learning (ML) algorithms to speed up GCM calculations and ultimately provide a more efficient description of nuclear energy spectra and other observables such as the NME of 0νββ decay without loss of accuracy.Method: To speed up GCM calculations, we propose a subspace reduction algorithm that employs optimized ML models as surrogates for exact quantum-number projection calculations for norm and Hamiltonian kernels. The model space of the original GCM is reduced to a subspace relevant for nuclear low energy spectra and the NME of ground state to ground state 0νββ decay based on the orthogonality condition (OC) and the energy transition-orthogonality procedure (ENTROP), respectively. Nuclear energy spectra are determined by the GCM through the configuration mixing within this subspace. For simplicity, a polynomial regression algorithm is used to learn the norm and Hamiltonian kernels. The efficiency and accuracy of this algorithm are illustrated for Ge 76 and Se 76 by comparing results obtained using the ML models to direct GCM calculations. The popular non-relativistic and relativistic EDFs, a valence-space shell-model Hamiltonian, and a modern nuclear interaction derived from chiral effective field theory are employed. Results:The low-lying energy spectra of 76 Ge and 76 Se, as well as the 0νββ-decay NME between their ground states, are computed. The results show that the performance of the GCM+OC/ENTROP+ML is more robust than that of the GCM+ML alone, and the former can reproduce the results of the original GCM calculation rather accurately with a significantly reduced computational cost.Conclusions: ML algorithms, when implemented properly, can accelerate GCM calculations without loss of accuracy. In applications with axially deformed configurations, the computation time can be reduced by a factor of three to nine for energy spectra and NMEs, respectively. This factor is expected to increase significantly with the number of employed generator coordinates.

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