Interacting Shell Model Calculations for Neutrinoless Double Beta Decay of 82Se With Left-Right Weak 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.

Status of the R2D2 project: A future neutrinoless double beta decay experiment

The nature of the neutrino is a central questions in physics. The search for neutrinoless double beta decay is the most sensitive experimental approach to demonstrate that the neutrino is a Majorana particle. Observation of such a rare process demands a detector with an excellent energy resolution, extremely low background, and a large mass of a double beta decaying isotope. R2D2 aims to develop a novel spherical high-pressure TPC that meets all the above requirements. As a first step, the energy resolution of the R2D2 prototype was measured. A 1.1% (FWHM) energy resolution was achieved for 5.3 MeV α-particles in Ar:CH4 at pressure up to 1.1 bar. This is a major milestone for R2D2 and paves the way for further studies with Xe gas and the possible use of this technology for neutrinoless double beta decay searches.

Texture One Zero Model Based on A4 Flavor Symmetry and its Implications to Neutrinoless Double Beta Decay

Neutrinos are perhaps the most elusive particles in our Universe. Neutrino physics could be counted as a benchmark for various new theories in elementary particle physics and also for the better understanding of the evolution of the Universe. To complete the neutrino picture, the missing information whether it is about their mass or their nature that the neutrinos are Majorana particles could be provided by the observation of a process called neutrinoless double beta (0νββ) decay. Neutrinoless double beta decay is a hypothesised nuclear process in which two neutrons simultaneously decay into protons with no neutrino emission. In this paper we proposed a neutrino mass model based on A4 symmetry group and studied its implications to 0νββ decay. We obtained a lower limit on |Mee| for inverted hierarchy and which can be probed in 0νββ experiments like SuperNEMO and KamLAND-Zen.