Effective double-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>-decay operator for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>76</mml:mn></mml:msup></mml:math>Ge and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>82</mml:mn></mml:msup></mml:math>Se

Holt, J. D.; Engel, J.

doi:10.1103/physrevc.87.064315

Cited by 66 publications

(78 citation statements)

References 35 publications

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“…Table V presents our new 124 Sn light neutrinoexchange 0νββ decay NME results with two SRC parametrizations (Argonne-V18 and CD-Bonn), together with the NME of five other nuclei from our group (ISM-CMU), 48 [40,48], compared with the most recent results that were obtained with nuclear structure methods that preserve the isospin symmetry and provide NME for both mechanisms. Included in Figure 6 (but not in Table V) are also shell model light neutrino-exchange NME for 48 Ca [87], 76 Ge, and 82 Se [88] that are using the same shell model calculations but an effective transition operator obtained in many-body perturbation theory. The updated IBM-2 NME [57] are only available for the Argonne-V18 SRC.…”

Section: Nuclear Matrix Elements Formentioning

confidence: 99%

Shell model predictions forSn124double-βdecay

Horoi¹,

Neacsu²

2016

Phys. Rev. C

131

194

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Neutrinoless double-beta (0νββ) decay is a promising beyond Standard Model process. Twoneutrino double-beta (2νββ) decay is an associated process that is allowed by the Standard Model, and it was observed in about 10 isotopes, including decays to the excited states of the daughter.124 Sn was the first isotope whose double-beta decay modes were investigated experimentally, and despite few other recent efforts, no signal has been seen so far. Shell model calculations were able to make reliable predictions for 2νββ decay half-lives. Here we use shell model calculations to predict the 2νββ decay half-life of 124 Sn. Our results are quite different from the existing quasiparticle randomphase approximation (QRPA) results, and we envision that they will be useful for guiding future experiments. We also present shell model nuclear matrix elements for two potentially competing mechanisms to the 0νββ decay of 124 Sn.

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Section: Nuclear Matrix Elements Formentioning

confidence: 99%

Shell model predictions forSn124double-βdecay

Horoi¹,

Neacsu²

2016

Phys. Rev. C

131

194

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“…An explanation of this behavior was recently provided [52], which suggests a path for improving of these NME. We believe that the nuclear shell model matrix elements are the most reliable, because they take into consideration all correlations around Fermi surface, respect all symmetries, and can take into account consistently the effects of the missing single particle space via many-body perturbation theory (shown to be small, about 20%, for 82 Se [26]). Because of that we use no quenching for the bare 0νββ operator in our calculations.…”

Section: νββ Decay Formalismmentioning

confidence: 99%

“…The range of these matrix elements is quite large due to their sensibility to the short-range correlations effects that were not treated consistently. One important improvement of these calculations would be obtaining an effective transition operator that takes into account consistently the short-range correlations effects, and the effects of the missing single particle orbits from the model space [26].…”

Section: Introductionmentioning

confidence: 99%

Analysis of mechanisms that could contribute to neutrinoless double-beta decay

Horoi

Neacsu

2016

Phys. Rev. D

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Neutrinoless double-beta decay, is a beyond the Standard Model process that would indicate that neutrinos are Majorana fermions and the lepton number is not conserved. It could be interesting to use the neutrinoless double-beta decay observations to distinguish between several beyond Standard Model mechanisms that could contribute to this process. Accurate nuclear structure calculations of the nuclear matrix elements necessary to analyze the decay rates could be helpful to narrow down the list of contributing mechanisms. We investigate the information one can get from the angular and energy distribution of the emitted electrons, and from the half-lives of several isotopes, assuming that the right-handed currents exist. For the analysis of these distributions we calculate the necessary nuclear matrix elements using shell model techniques, and we explicitly consider interference terms.

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“…The first such calculations show an enhancement for the light-neutrino NME of 20% for 76 Ge and 30% for 82 Se [27]. Other models such and QRPA and IBM treat the pairing aspect differently.…”

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confidence: 99%

Nuclear Structure Aspects of Neutrinoless Double-βDecay

2014

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We decompose the neutrinoless double-beta decay matrix elements into sums of products over the intermediate nucleus with two less nucleons. We find that the sum is dominated by the J π = 0 + ground state of this intermediate nucleus for both the light and heavy neutrino decay processes. This provides a new theoretical tool for comparing and improving nuclear structure models. It also provides the connection to two-nucleon transfer experiments.PACS numbers: 23.40. Bw, 21.60.Cs, 23.40.Hc, 14.60.Pq Neutrinoless double beta decay 0νββ is one of the most important current topics in physics that provides unique information on the neutrino properties [1], [2], [3]. The 0νββ decay process and the associated nuclear matrix elements (NME) were investigated by using several approaches including the quasiparticle random phase approximation (QRPA) [1], the interacting shell model [4], [5], the interacting boson model [6], [7], the generator coordinate method [8], and the projected Hartree-Fock Bogoliubov model [9]. It is critical to assess which nuclei are the best candidates for experimental study.Since the experimental decay rate is proportional to the square of the calculated nuclear matrix elements, it is important to calculate these matrix elements with high accuracy to be able to extract the neutrino effective mass which can be used to determine the absolute scale of neutrino masses. However, the theoretical methods used give results that differ from one another by factors of up to 2-3. It is important to understand the nuclear structure aspects of these matrix elements and why the models give differing results. In this Letter we present a new theoretical tool for understanding 0νββ matrix elements by expanding them in terms of a summation over states in the nucleus with two less nucleons (A − 2). We show that the matrix elements are dominated by the contribution through the ground state of the (A − 2) intermediate nucleus. We also show that the lightneutrino matrix elements are dominated by the GamowTeller type operator that is proportional to a schematic interaction of the form σ 1 · σ 2 /r. This opens up new ways of comparing theoretical models and improving the accuracy of the NME for 0νββ decay.The 0νββ process can be naturally described in 2 nd order perturbation theory, in which the energies of the virtual states of the intermediate nucleus obtained by a single beta decay of the parent nucleus enter into the propagator. However, it has been known for some time (see e.g. [10], [11] and references therein) that these energies are small compared to the neutrino exchange energy, and therefore the widely used closure approximation replaces these energies by a constant value and sums-out the contribution of the intermediate states. We will start with the case for the 0νββ decay of 76 Ge that is shown in Fig. 1. Previously, the structure dependence has been analyzed in terms of the "chargeexchange" to intermediate states in 76 As. In contrast, we will show the results for expanding in terms of the intermediate stat...

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Effective double-β-decay operator for76Ge and82Se

Cited by 66 publications

References 35 publications

Shell model predictions forSn124double-βdecay

Shell model predictions forSn124double-βdecay

Analysis of mechanisms that could contribute to neutrinoless double-beta decay

Nuclear Structure Aspects of Neutrinoless Double-βDecay

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