Abstract
The two-neutrino double-beta decay (2νββ-decay) process is attracting more and more attention of the physics community due to its potential to explain nuclear structure aspects of involved atomic nuclei and to constrain new (beyond the Standard model) physics scenarios. Topics of interest are energy and angular distributions of the emitted electrons, which might allow the deduction of valuable information about fundamental properties and interactions of neutrinos once a new generation of the double-beta decay experiments will be realized. These tasks require an improved theoretical description of the 2νββ-decay differential decay rates, which is presented. The dependence of the denominators in nuclear matrix elements on lepton energies is taken into account via the Taylor expansion. Both the Fermi and Gamow-Teller matrix elements are considered. For nuclei of experimental interest, relevant phase-space factors are calculated by using exact Dirac wave functions with finite nuclear size and electron screening. The uncertainty of the angular correlation factor on nuclear structure parameters is discussed. It is emphasized that the effective axial-vector coupling constant gAeff can be determined more reliably by accurately measuring the angular correlation factor.
Highlights
The different behavior of GN and HN, for the same approximations schemes for the electronic wave functions, indicates that the angular correlation is sensitive to the treatment of the Coulomb interaction for the emitted electrons
The theoretical description of the angular distribution of outgoing electrons is achieved by considering the effect of lepton energies in energy denominators of the nuclear matrix elements via the Taylor expansion
A non-zero ξ 31 is a signature of the dominance of the
Summary
There is an increased interest in the two-neutrino double-beta decay (2νββ-decay) mode with an emission of two electrons and two antineutrinos published maps and institutional affil-. The 2νββ-decay is the second order process of weak interaction fully consistent with the Standard model (SM) of particle physics, where two neutrons are simultaneously transformed into two protons inside an atomic nucleus, and two pairs of electrons and antineutrinos are emitted. The theoretical description of the shape of single and summed electron energy distributions of the 2νββ-decay has been significantly improved by taking into account the dependence on lepton energies from the energy denominators of nuclear matrix elements [6], which was commonly neglected Their importance was already manifested by the study of 2νββ-decay energy and angular distributions within the framework of the Single State Dominance (SSD) versus Higher State Dominance (HSD). For nuclei of experimental interest, all phase-space factors are calculated by using exact Dirac wave functions with finite nuclear size and electron screening
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
