0000000000215255
AUTHOR
L. Jokiniemi
Two-neutrino ββ decay of 136Xe to the first excited 0+ state in 136Ba
We calculate the nuclear matrix element for the two-neutrino $\beta\beta$ decay of $^{136}$Xe into the first excited $0^+$ state of $^{136}$Ba. We use different many-body methods: the quasiparticle random-phase approximation (QRPA) framework, the nuclear shell model, the interacting boson model (IBM-2), and an effective field theory (EFT) for $\beta$ and $\beta\beta$ decays. While the QRPA suggests a decay rate at the edge of current experimental limits, the shell model points to a half-life about two orders of magnitude longer. The predictions of the IBM-2 and the EFT lie in between, and the latter provides systematic uncertainties at leading order. An analysis of the running sum of the nu…
Comparative analysis of muon-capture and 0νββ-decay matrix elements
Average matrix elements of ordinary muon capture (OMC) to the intermediate nuclei of neutrinoless double beta (0νββ) decays of current experimental interest are computed and compared with the corresponding energy and multipole decompositions of 0νββ-decay nuclear matrix elements (NMEs). The present OMC computations are performed using the Morita-Fujii formalism by extending the original formalism beyond the leading order. The 0νββ NMEs include the appropriate short-range correlations, nuclear form factors, and higher-order nucleonic weak currents. The nuclear wave functions are obtained in extended no-core single-particle model spaces using the spherical version of the proton-neutron quasip…
Pinning down the strength function for ordinary muon capture on Mo
Ordinary muon capture (OMC) on $^{100}$Mo is studied both experimentally and theoretically in order to access the weak responses in wide energy and momentum regions. The OMC populates states in $^{100}$Nb up to some 50 MeV in excitation energy. For the first time the associated OMC strength function has been computed and compared with the obtained data. The present computations are performed using the Morita-Fujii formalism of OMC by extending the original formalism beyond the leading order. The participant nuclear wave functions are obtained in extended no-core single-particle model space using the spherical version of proton-neutron quasiparticle random-phase approximation (pnQRPA) with t…
High-precision Q-value measurement and nuclear matrix element calculations for the double-β decay of 98Mo
The 98Mo double-beta decay Q-value has been measured, and the corresponding nuclear matrix elements of neutrinoless double-beta (0νββ) decay and the standard two-neutrino double-beta (2νββ) decay have been provided by nuclear theory. The double-beta decay Q-value has been determined as Qββ=113.668(68) keV using the JYFLTRAP Penning trap mass spectrometer. It is in agreement with the literature value, Qββ=109(6) keV, but almost 90 times more precise. Based on the measured Q-value, precise phase-space factors for 2νββ decay and 0νββ decay, needed in the half-life predictions, have been calculated. Furthermore, the involved nuclear matrix elements have been computed in the proton–neutron quasi…
High-precision Q-value measurement and nuclear matrix element calculations for the double-$$\beta $$ decay of $$^{98}$$Mo
AbstractThe $$^{98}$$ 98 Mo double-beta decay Q-value has been measured, and the corresponding nuclear matrix elements of neutrinoless double-beta ($$0\nu \beta \beta $$ 0 ν β β ) decay and the standard two-neutrino double-beta ($$2\nu \beta \beta $$ 2 ν β β ) decay have been provided by nuclear theory. The double-beta decay Q-value has been determined as $$Q_{\beta \beta }=113.668(68)$$ Q β β = 113.668 ( 68 ) keV using the JYFLTRAP Penning trap mass spectrometer. It is in agreement with the literature value, $$Q_{\beta \beta }=109(6)$$ Q β β = 109 ( 6 ) keV, but almost 90 times more precise. Based on the measured Q-value, precise phase-space factors for $$2\nu \beta \beta $$ 2 ν β β deca…
Ab initio calculation of muon capture on $^{24}$Mg
In this work we study ordinary muon capture (OMC) on $^{24}$Mg from a first principles perspective. Starting from a particular two- and three-nucleon interaction derived from chiral effective field theory, we use the valence-space in-medium similarity renormalization group (VS-IMSRG) framework to construct effective Hamiltonians and muon-capture operators which nonperturbatively account for many-body physics outside the valence space. The obtained nuclear matrix elements are compared against those from the phenomenological shell model. The impact of including the correlations from the nuclear shell model (NSM) as well as including the induced two-body part is studied in detail. Furthermore,…
Muon-capture strength functions in intermediate nuclei of 0νββ decays
Capture rates of ordinary muon capture (OMC) to the intermediate nuclei of neutrinoless double beta (0νββ) decays of current experimental interest are computed. The corresponding OMC (capture-rate) strength functions have been analyzed in terms of multipole decompositions. The computed low-energy OMC-rate distribution to 76 As is compared with the available data of Zinatulina et al. [Phys. Rev. C 99, 024327 (2019)]. The present OMC computations are performed using the Morita-Fujii formalism by extending the original formalism beyond the leading order. The participant nuclear wave functions are obtained in extended no-core single-particle model spaces using the spherical version of proton-ne…