Improved description of the 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>2</mml:mn><mml:mi>ν</mml:mi><mml:mi>β</mml:mi><mml:mi>β</mml:mi></mml:mrow></mml:math>
-decay and a possibility to determine the effective axial-vector coupling constant

Šimkovic, F.; Dvornický, R.; Štefánik, Dušan; Faessler, Amand

doi:10.1103/physrevc.97.034315

Cited by 51 publications

(73 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also, the α parameter calculated by disregarding the global phase shift in this work seems to agree better with the results published in Kotila and Iachello [11]. New calculations concerning the energy distributions were recently reported in Simkovic et al [48], where modifications of the shape of the energy distributions were evidenced.…”

Section: Energy and Angular Distributionssupporting

confidence: 89%

Phase Space Factors for Double-Beta Decays

Stoica

Mirea

2019

Front. Phys.

View full text Add to dashboard Cite

Double-beta decay is presently a very studied process both theoretically and experimentally due to its potential to provide valuable information about important, but still unknown issues related to the neutrino properties and conservation of some symmetries. In the theoretical study of the double-beta decay two key quantities entering the half-life formulas are important, namely the phase space factors embedding the influence of the Coulomb field of the daughter nucleus on the emitted electrons/positrons, and the nuclear matrix elements embedding the nuclear structure effects of the nuclei participating in the decay. Accurate calculation of both of them are needed for good predictions of the double-beta decay half-lives and transitions still unmeasured, and for constraining various beyond Standard Model parameters associated with mechanisms that may contribute to the neutrinoless double-beta decay modes. During time much attention has been paid to the nuclear matrix elements that were considered to bring the largest uncertainties in the computation of the double-beta decay halflives, while the phase space factors were considered until the recent past to be computed with enough precision. However, newer computation of the phase space factors performed with more precise methods revealed relevant deviations from their values reported previously, especially for heavier nuclei and for positron emitting and electron capture decay modes. In this paper we review the progress made in the computation of the phase space factors for double beta decay. We begin with the nonrelativistic approaches, continue with the relativistic approaches which use approximate electron/positron wave functions, and end up with recent, more precise, computations of the phase space factors where exact electron wave functions are obtained from the resolution of a Dirac equation in a Coulomb-type potential and with inclusion of finite nuclear size and screening effects. We report an up-dated and complete list of the phase space factors (PSF) for the following DBD modes: β − β − , β + β + , ECβ + , and ECEC and for transitions to final ground and first excited 2 + and 0 + states of the daughter nuclei. We also make a comparison between different values of the phase space factors found in literature and discuss the differences between these results.

show abstract

Section: Energy and Angular Distributionssupporting

confidence: 89%

Phase Space Factors for Double-Beta Decays

Stoica

Mirea

2019

Front. Phys.

View full text Add to dashboard Cite

show abstract

“…GT−3 [25,40], multiplied by the corresponding ðg eff A Þ 2 . The sums run over the excitation energy of the spin-parity 1 þ states in the intermediate nucleus 136 Cs.…”

Section: νmentioning

confidence: 99%

“…These achievements demand an improved theoretical description. Reference [40] gives a more accurate expression for the 2νββ decay rate…”

mentioning

confidence: 99%

Precision Analysis of the Xe136 Two-Neutrino ββ Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements

Gando¹,

Gando²,

Hachiya³

et al. 2019

Phys. Rev. Lett.

View full text Add to dashboard Cite

We present a precision analysis of the 136 Xe two-neutrino ββ electron spectrum above 0.8 MeV, based on highstatistics data obtained with the KamLAND-Zen experiment. An improved formalism for the two-neutrino ββ rate allows us to measure the ratio of the leading and subleading 2νββ nuclear matrix elements (NMEs), ξ 2ν 31 ¼ −0.26 þ0.31 −0.25. Theoretical predictions from the nuclear shell model and the majority of the quasiparticle random-phase approximation (QRPA) calculations are consistent with the experimental limit. However, part of the ξ 2ν 31 range allowed by the QRPA is excluded by the present measurement at the 90% confidence level. Our analysis reveals that predicted ξ 2ν 31 values are sensitive to the quenching of NMEs and the competing contributions from low-and high-energy states in the intermediate nucleus. Because these aspects are also at play in neutrinoless ββ decay, ξ 2ν 31 provides new insights toward reliable neutrinoless ββ NMEs.

show abstract

“…Experiments studying the 2νβ β -decay are currently approaching a qualitatively new level, where high-precision measurements are performed not only for half-lives but also for differential characteristics of the process. Recently, by taking into account dependence of energy denominators on lepton energies via the Taylor expansion a more accurate expression for the 2νβ β -decay halflife was derived [6]. The revised expression includes in addition to the well-known nuclear matrix element M 2ν…”

Section: Pos(now2018)064mentioning

confidence: 99%

“…GT also the double GT matrix element M 2ν GT −3 with energy denominator to the third power. A novel method to determine g eff A was proposed, which requires to measure a ratio of these two matrix elements from the energy and angular distributions of emitted electrons [6].…”

Section: Pos(now2018)064mentioning

confidence: 99%

Neutrinoless double beta decay: Theory challenges

Šimkovic¹

2019

Proceedings of Neutrino Oscillation Workshop — PoS(NOW2018)

Self Cite

View full text Add to dashboard Cite

The recent progress in theoretical description of the neutrinoless double beta decay (0νβ β-decay) is briefly reviewed. By taking advantage of an interpolating formula, which allows to calculate the 0νβ β-decay half-life for an arbitrary neutrino mass and which is expressed with a single nuclear matrix element, neutrino mass mechanisms of this process having origin in the left-right symmetric models are discussed. To understand the importance of the mass mechanism due to right-handed leptonic current, an assumption about seesaw-type 6 × 6 unitary neutrino mixing matrix and relation of light and heavy neutrino masses is made. The region of dominance of right over left leptonic current mechanisms is identified. Further, a progress in the calculation of double beta decay nuclear matrix elements within the quasiparticle random phase approximation is reported. A connection between the two neutrino double-beta decay and 0νβ β-decay matrix elements is discussed. An impact of the quenching of the axial-vector coupling constant g A on double-beta decay processes is addressed and a possibility to determine quenched value of g A is announced.

show abstract

Improved description of the 2νββ -decay and a possibility to determine the effective axial-vector coupling constant

Cited by 51 publications

References 33 publications

Phase Space Factors for Double-Beta Decays

Phase Space Factors for Double-Beta Decays

Precision Analysis of the Xe136 Two-Neutrino ββ Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements

Neutrinoless double beta decay: Theory challenges

Contact Info

Product

Resources

About