Neutrino Masses and Right-Handed Weak Currents Studied by Neutrino-Less ββ -Decay Detectors.

Detecting neutrino-less double beta ( 0 ν β β ) decay with high-sensitivity 0 ν β β detectors is of current interest for studying the Majorana neutrino's nature, the neutrino mass (ν -mass), right-handed weak currents (RHCs), and others beyond the Standard Model. Many experimental groups have studied 0 ν β β decay with ν -mass sensitivities on the order of 100 meV and RHC sensitivities on the order of 10   − 9 –10   − 6 , but no clear 0 ν β β signals have been observed so far in these ν -mass and RHC regions. Thus, several experimental groups are developing higher-sensitivity detectors to explore a smaller ν -mass region around 15–50 meV, which corresponds to the inverted hierarchy ν -mass, and smaller RHC regions on the order of 10   − 10 –10   − 7 in the near future. Nuclear matrix elements (NMEs) for ν -mass and RHC processes are crucial for extracting the ν -mass and RHCs of particle physics interest from 0 ν β β experiments. This report briefly reviews detector sensitivities and upper limits on the ν -mass and right-handed currents for several current 0 ν β β detectors and the ν -mass and RHC sensitivities expected for some near-future ones. [ABSTRACT FROM AUTHOR]