Double Beta Decays and Neutrino Masses

DOI Web Site Web Site BIBCODE 15 Citations 291 References
  • Ejiri Hiroyasu
    Natural Science, International Christian University Japan Synchrotron Radiation Research Institute Research Center for Nuclear Physics, Osaka University

Search this article

Abstract

Neutrino-less double beta decays (0νββ), which violate the lepton number conservation law by ΔL=2, are of great interest for studying the fundamental properties of neutrinos beyond the standard electroweak theory. High-sensitivity 0νββ studies with mass sensitivities of the solar and atmospheric ν-masses are crucial for studying the Majorana nature of ν’s, the ν mass spectrum, the absolute ν-mass scale, the Majorana CP phases and other fundamental properties of neutrinos and weak interactions. Actually, high-sensitivity experiments of 0νββ are the unique and practical method for studying all these fundamental properties of neutrinos in the foreseeable future. On the basis of the recent ν oscillation studies, the effective mass sensitivity required for observing the 0νββ rate is of the order of the atmospheric ν mass scale of δmA∼50 meV in the case of the inverted mass hierarchy and of the order of the solar ν mass scale of δmS∼8 meV in the case of the normal hierarchy. The present ββ detectors with sensitivities of 150–300 meV are effective in the case of the quasi-degenerate ν mass spectrum. Future detectors with higher sensitivities of the orders of δmA–δmS, using different nuclei and methods (calorimetric, spectroscopic), are indispensable for establishing 0νββ. Theoretical and experimental studies for evaluating nuclear matrix elements M0ν within 20–30% are important for extracting the sensible ν mass from the 0νββ rate. Charge exchange reactions by means of nuclear, electron and ν probes provide useful data for M0ν. International collaboration for experimental and theoretical ββ works are encouraged to perform next-generation ββ experiments. High-sensitivity ββ detectors can be used for studying rare nuclear processes such as solar ν’s, dark matter, charge nonconservation, and nucleon decays. This report is a brief review of double beta decays and neutrinos with emphasis on high-sensitivity 0νββ studies for the Majorana ν mass.

Journal

Citations (15)*help

See more

References(291)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top