https://biblio.ugent.be/publication/685594/file/1130605.pdf

Review of Particle Physics

/pdf/review-of-particle-physics-1996-1997-jeg703df6k.pdf

Review of Particle Physics, 1996-1997

The theoretical and experimental issues relevant to neutrinoless double beta decay are reviewed. The impact that a direct observation of this exotic process would have on elementary particle physics, nuclear physics, astrophysics, and cosmology is profound. Now that neutrinos are known to have mass and experiments are becoming more sensitive, even the nonobservation of neutrinoless double beta decay will be useful. If the process is actually observed, we will immediately learn much about the neutrino. The status and discovery potential of proposed experiments are reviewed in this context, with significant emphasis on proposals favored by recent panel reviews. The importance of and challenges in the calculation of nuclear matrix elements that govern the decay are considered in detail. The increasing sensitivity of experiments and improvements in nuclear theory make the future exciting for this field at the interface of nuclear and particle physics.

/pdf/double-beta-decay-majorana-neutrinos-and-neutrino-mass-2tfhqvhys8.pdf

Double Beta Decay, Majorana Neutrinos, and Neutrino Mass

The data of the Heidelberg–Moscow double beta decay experiment for the measuring period August 1990–May 2000 (54.9813 kg y or 723.44 molyears), published recently, are analyzed using the potential of the Bayesian method for low counting rates. First evidence for neutrinoless double beta decay is observed giving first evidence for lepton number violation. The evidence for this decay mode is 97% (2.2σ) with the Bayesian method, and 99.8% c.l. (3.1σ) with the method recommended by the Particle Data Group. The half-life of the process is found with the Bayesian method to be $T_{1/2}^{0\nu} = (0.8\hbox{--}18.3)\times 10^{25}~{\rm y}$ (95% c.l.) with a best value of 1.5 × 1025y. The deduced value of the effective neutrino mass is, with the nuclear matrix elements from Ref. 1, = (0.11–0.56) eV (95% c.l.), with a best value of 0.39 eV. Uncertainties in the nuclear matrix elements may widen the range given for the effective neutrino mass by at most a factor 2. Our observation which at the same time means evide...

Evidence for neutrinoless double beta decay

Weak-interaction and nuclear-structure aspects of nuclear double beta decay

Developments in the theoretical investigation of nuclear double-beta decay are reviewed. In particular, the neutrinoless mode is discussed in detail, since it is sensitive to lepton number violation as predicted by gauge theories beyond the standard model and it is expected to give important information on the nature of the neutrinos and the weak interaction. Various approximations made in the theoretical treatment of neutrinoless and two-neutrino double beta decay are examined, and the limits on the effective Majorana mass of the electron neutrino as well as the coupling constants of the right-handed leptonic current are presented.

http://iopscience.iop.org/article/10.1088/0034-4885/54/1/002/pdf

T Tomoda

Papers

Double beta decay