We discuss the variation of the nuclear matrix element (NME) for the neutrinoless double beta ($0νββ$) decay of $^{76}$Ge when the wave functions are constrained to reproduce the experimental occupancies of the two nuclei involved in the transition. In the Interacting Shell Model description the value of the NME is enhanced about 15% compared to previous calculations, whereas in the QRPA the NME's are reduced by 20%-30%. This diminishes the discrepancies between both approaches. In addition, we discuss effect of the short range correlations on the NME in the light of the recently proposed parametrizations based on a consistent renormalization of the $0νββ$ transition operator.
Nuclear matrix elements (NMEs) for neutrinoless double beta decays (DBDs) are required for studying neutrino physics beyond the standard model by DBD. The experimental spin-dipole (SD) giant resonance energy and the SD strength are shown for the first time to be closely related to the DBD-NME, and are used for studying the spin-isospin correlation and the quenching of the axial-vector coupling. So they are used to help the theoretical model calculation of the DBD-NME.
The nuclear matrix elements of neutrinoless double-$β$ decay for nuclei $^{76}$Ge, $^{82}$Se, $^{100}$Mo, $^{130}$Te, and $^{150}$Nd are studied within the triaxial projected shell model, which incorporates simultaneously the triaxial deformation and quasiparticle configuration mixing. The low-lying spectra and the $B(E2:0^+\rightarrow2^+)$ values are reproduced well. The effects of the quasiparticles configuration mixing, the triaxial deformation, and the closure approximation on the nuclear matrix elements are studied in detail. For nuclei $^{76}$Ge, $^{82}$Se, $^{100}$Mo, $^{130}$Te, and $^…
Employing the PHFB model, nuclear transition matrix elements $M^{\left( K\right) }$ for the neutrinoless double-$β^{-} $ decay of $\ ^{76}$Ge and $^{82}$Se isotopes are calculated within mechanisms involving light as well as heavy Majorana neutrinos, and classical Majorons by considering the spin-tensor decomposition of realistic KUO and empirical JUN45 effective two-body interaction. It is noticed that the effects due to the SRC on NTMEs $M^{\left( 0ν\right) }$ and $M^{\left( 0N\right) }$ due to the exchange of light and heavy Majorana neutrinos, respectively, is maximally incorporated by the…
Uncertainties in nuclear transition matrix elements for $β^{+}β^{+}$ and $\varepsilon β^{+}$ modes of neutrinoless positron double-$β$ decay within PHFB model
We compute nuclear matrix elements of neutrinoless double-beta decay mediated by light Majorana-neutrino exchange in the A = 6 system. The goal is to benchmark two many-body approaches, the No-Core Shell Model and the Multi-Reference In-Medium Similarity Renormalization Group. We use the SRG-evolved chiral N3LO-EM500 potential for the nuclear interaction, and make the approximation that isospin is conserved. We compare the results of the two approaches as a function of the cutoff on the many-body basis space. Although differences are seen in the predicted nuclear radii, the ground-state energi…
Ab initio short-range nuclear matrix elements for neutrinoless double-beta decay
TRIUMF（特柳姆夫实验室）；McGill University（麦吉尔大学）；University of British Columbia（不列颠哥伦比亚大学）；Massachusetts Institute of Technology（麻省理工学院）；Technische Universität Darmstadt（达姆施塔特工业大学）；ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH（极端物质研究所EMMI，GSI重离子研究中心有限公司）
Employing the projected-Hartree-Fock-Bogoliubov (PHFB) model in conjunction with four different parametrizations of pairing plus multipolar effective two body interaction and three different parametrizations of Jastrow short range correlations, nuclear transition matrix elements for the neutrinoless double-$β$ decay of $^{94,96}$Zr, $^{100}$Mo, $^{110}$Pd, $^{128,130}$Te and $^{150}$Nd isotopes are calculated within mechanisms involving light Majorana neutrino mass and right handed current. Statistically, model specific uncertainties in sets of twelve nuclear transition matrix elements are est…
We use coupled-cluster theory and nuclear interactions from chiral effective field theory to compute the nuclear matrix element for the neutrinoless double-beta decay of $^{48}$Ca. Benchmarks with the no-core shell model in several light nuclei inform us about the accuracy of our approach. For $^{48}$Ca we find a relatively small matrix element. We also compute the nuclear matrix element for the two-neutrino double-beta decay of $^{48}$Ca with a quenching factor deduced from two-body currents in recent ab-initio calculation of the Ikeda sum-rule in $^{48}$Ca [Gysbers et al., Nature Physics 15,…
Statistical shell model for neutrinoless double $β$-decay nuclear transition matrix elements: Results for $^{76}$Ge, $^{82}$Se, $^{100}$Mo, $^{124}$Sn, $^{130}$Te and $^{136}$Xe
Starting from chiral nuclear interactions, we evaluate the contribution of the leading-order contact transition operator to the nuclear matrix element (NME) of neutrinoless double-beta decay, assuming a light Majorana neutrino-exchange mechanism. The corresponding low-energy constant (LEC) is determined by fitting the transition amplitude of the $nn\to ppe^-e^-$ process to a recently proposed synthetic datum. We examine the dependence of the amplitude on similarity renormalization group (SRG) scale and chiral expansion order of the nuclear interaction, finding that both dependences can be comp…
We introduce the formalism to describe heavy-ion Double-Charge-Exchange (DCE) processes in the eikonal approximation. We focus on the low-momentum-transfer limit -- corresponding to the differential cross section at $θ=0^\circ$ -- and, for the first time, we show that it is possible to factorize the DCE cross-section in terms of reaction and nuclear parts. Whereas in the $θ\neq0^\circ$ case the nuclear part is a convolution of the beam and target nuclear matrix elements (NMEs), for $θ=0^\circ$ we demonstrate - for the first time- that the transition matrix elements can be written as the sum of…
Nuclear deformation and neutrinoless double-$β$ decay of $^{94,96}$Zr, $^{98,100}$Mo, $^{104}$Ru, $^{110}$Pd, $^{128,130}$Te and $^{150}$Nd nuclei in mass mechanism
Uncertainty Quantification of the $^{76}$Ge Neutrinoless Double-Beta Decay Nuclear Matrix Element
Central Michigan University（中密歇根大学）；International Center for Advanced Training and Research in Physics (CIFRA)（国际高级培训与物理研究中心）；Institute of Atomic Physics (IFA)（原子物理研究所）
