scholarly journals Constraints on Heavy Neutrino and SUSY Parameters Derived from the Study of Neutrinoless Double Beta Decay

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Andrei Neacsu ◽  
Sabin Stoica
Keyword(s):  
Phase Space ◽  
Shell Model ◽  
Beta Decay ◽  
Nuclear Matrix ◽  
Neutrinoless Double Beta Decay ◽  
Lepton Number ◽  
Double Beta Decay ◽  
Heavy Neutrino ◽  
Matrix Elements ◽  
Lepton Number Violating

New constraints on the lepton number violating (LNV) parameters are derived from the analysis of the neutrinoless double beta (0νββ) decay in the hypothesis that this process would occur through the exchange of heavy neutrinos and/or SUSY particles. For derivation, we use new values of both phase space factors (PSFs) and nuclear matrix elements (NMEs) calculated with numerical codes developed recently, as well as the most recent experimental lifetimes. The NMEs are computed with a shell model (ShM) code for 48Ca, 76Ge, and 82Senuclei, while at present similar ShM results are available only for the first nucleus. We compare our results with similar ones from literature, obtained with ShM, QRPA, and IBM-2 methods, and conclude that more results are needed for a relevant analysis on the validity of NMEs associated with these decay mechanisms.

Nuclear matrix elements of neutrinoless double beta decay for masses 130 and 136 in the shell model

2020 ◽  
Vol 47 (3) ◽  
pp. 035102
Author(s):  
K Higashiyama ◽  
K Yanase ◽  
N Yoshinaga ◽  
A Umeya ◽  
A Uehara ◽  
...  
Keyword(s):  
Shell Model ◽  
Beta Decay ◽  
Nuclear Matrix ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Matrix Elements

scholarly journals Interacting Shell Model Calculations for Neutrinoless Double Beta Decay of 82Se With Left-Right Weak Boson Exchange

2021 ◽  
Vol 8 ◽  
Author(s):  
Yoritaka Iwata ◽  
Shahariar Sarkar
Keyword(s):  
Shell Model ◽  
Beta Decay ◽  
Nuclear Matrix ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Matrix Elements ◽  
Model Framework ◽  
Weak Boson ◽  
Model Calculations ◽  
Boson Exchange

In the present work, the λ mechanism (left-right weak boson exchange) and the light neutrino-exchange mechanism of neutrinoless double beta decay is studied. In particular, much attention is paid to the calculation of nuclear matrix elements for one of the neutrinoless double beta decaying isotopes 82Se. The interacting shell model framework is used to calculate the nuclear matrix element. The widely used closure approximation is adopted. The higher-order effect of the pseudoscalar term of nucleon current is also included in some of the nuclear matrix elements that result in larger Gamow-Teller matrix elements for the λ mechanism. Bounds on Majorana neutrino mass and lepton number violating parameters are also derived using the calculated nuclear matrix elements.

scholarly journals Variation of NMEs of 0νββ for 48Ca with different components of NN interaction

2019 ◽  
Vol 223 ◽  
pp. 01057
Author(s):  
Shahariar Sarkar ◽  
Pawan Kumar ◽  
Kanhaiya Jha ◽  
P.K. Raina
Keyword(s):  
Beta Decay ◽  
Nuclear Matrix ◽  
Model Space ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Central Component ◽  
Spin Orbit ◽  
Matrix Elements ◽  
Nucleon Interaction ◽  
Total Interaction

We examine the sensitivity of nuclear matrix elements (NMEs) for light-neutrino exchange mechanism of neutrinoless double beta decay (0νββ) for 48Ca to the various components of two-nucleon interaction, GXPF1A, in fp model space. It is found that the contribution in NMEs coming from the central component is close to contribution from total interaction. The spin-orbit and tensor components are found canceling the contribution of each other.

scholarly journals CONSTRAINTS OF MIXING ANGLES FROM LEPTON NUMBER VIOLATING PROCESSES

1999 ◽  
Vol 14 (06) ◽  
pp. 433-445 ◽  
Author(s):  
HIROYUKI NISHIURA ◽  
KOUICHI MATSUDA ◽  
TAKESHI FUKUYAMA
Keyword(s):  
Beta Decay ◽  
Neutrinoless Double Beta Decay ◽  
Lepton Number ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Mixing Angles ◽  
Left Handed ◽  
Majorana Neutrinos ◽  
Mixing Matrix ◽  
Lepton Number Violating

We discuss the constraints of lepton mixing angles from lepton number violating processes such as neutrinoless double beta decay, μ--e+ conversion and K decay, K-→π+μ-μ- which are allowed only if neutrinos are Majorana particles. The rates of these processes are proportional to the averaged neutrino mass defined by [Formula: see text] in the absence of right-handed weak coupling. Here a, b(j) are flavor(mass) eigenstates and Uaj is the left-handed lepton mixing matrix. We give general conditions imposed on <mν>ab in terms of mi, lepton mixing angles and CP violating phases (three phases in Majorana neutrinos). These conditions are reduced to the constraints among mi, lepton mixing angles and <mν>ab which are irrelevant to the concrete values of CP phases. Given a <mν>ab experimentally, these conditions constrain mi and the lepton mixing angles. Though these constraints are still loose except for neutrinoless double beta decay, they will become helpful through rapid improvements of experiments. By using these constraints we also derive the limits on averaged neutrino masses for μ--e+ conversion and K decay, K-→π+μ-μ-, respectively. We also present the bounds for CP phases in terms of mi, mixing angles and <mν>ab.

scholarly journals EVIDENCE FOR NEUTRINOLESS DOUBLE BETA DECAY

2001 ◽  
Vol 16 (37) ◽  
pp. 2409-2420 ◽  
Author(s):  
H. V. KLAPDOR-KLEINGROTHAUS ◽  
A. DIETZ ◽  
H. L. HARNEY ◽  
I. V. KRIVOSHEINA
Keyword(s):  
Beta Decay ◽  
Neutrino Mass ◽  
Nuclear Matrix ◽  
Bayesian Method ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Matrix Elements ◽  
Majorana Particle ◽  
Best Value ◽  
Measuring Period

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 [Formula: see text] (95% c.l.) with a best value of 1.5 × 1025 y . The deduced value of the effective neutrino mass is, with the nuclear matrix elements from Ref. 1, <m> = (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 evidence that the neutrino is a Majorana particle, will be of fundamental importance for neutrino physics.

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