Werner Rodejohann

Theory of neutrinos: a white paper

This paper is a review of the present status of neutrino mass physics, which grew out of an APS sponsored study of neutrinos in 2004. After a discussion of the present knowledge of neutrino masses and mixing and some popular ways to probe the new physics implied by recent data, it summarizes what can be learned about neutrino interactions as well as the nature of new physics beyond the Standard Model from the various proposed neutrino experiments. The intriguing possibility that neutrino mass physics may be at the heart of our understanding of a long standing puzzle of cosmology, i.e. the origin of matter?antimatter asymmetry is also discussed.

NEUTRINO-LESS DOUBLE BETA DECAY AND PARTICLE PHYSICS

We review the particle physics aspects of neutrino-less double beta decay. This process can be mediated by light massive Majorana neutrinos (standard interpretation) or by something else (non-standard interpretations). The physics potential of both interpretations is summarized and the consequences of future measurements or improved limits on the half-life of neutrino-less double beta decay are discussed. We try to cover all proposed alternative realizations of the decay, including light sterile neutrinos, supersymmetric or left-right symmetric theories, Majorons, and other exotic possibilities. Ways to distinguish the mechanisms from one another are discussed. Experimental and nuclear physics aspects are also briefly touched, alternative processes to double beta decay are discussed, and an extensive list of references is provided.

Neutrinoless double-beta decay and neutrino physics

The connection of neutrino physics with the neutrinoless double-beta decay is reviewed. After presenting the current status of the Pontecorvo–Maki–Nakagawa–Sakata matrix and the theoretical background of neutrino mass and lepton mixing, we will summarize the various implications of neutrino physics for the double-beta decay. The influence of light sterile neutrinos and other exotic modifications of the three neutrino picture is also discussed.

On the Connection of Leptogenesis with Low Energy CP Violation and LFV Charged Lepton Decays

Assuming only a hierarchical structure of the heavy Majorana neutrino masses and of the neutrino Dirac mass matrix mD of the see–saw mechanism, we find that in order to produce the observed baryon asymmetry of the Universe via leptogenesis, the scale of mD should be given by the up–quark masses. Lepton flavor violating decays µ → e+, � → µ+ and � → e+ are considered and a characteristic relation between their decay rates is predicted. The effective Majorana mass in neutrinoless double beta decay depends on the CP violating phase controlling the leptogenesis if one of the heavy Majorana neutrinos is much heavier than the other two. Successful leptogenesis requires a rather mild mass hierarchy between the latter. The indicated hierarchical relations are also compatible with the low-energy neutrino mixing phenomenology. The scenario under study is compatible with the low–energy neutrino mixing phenomenology. The CP violation effects in neutrino oscillations can be observable. In general, there is no direct connection between the latter and the CP violation in leptogenesis. If the CP violating phases of the see–saw model satisfy certain relations, the baryon asymmetry of the Universe and the rephasing invariant JCP which determines the magnitude of the CP violation effects in neutrino oscillations, depend on the same CP violating phase and their signs are correlated.

Elements of the neutrino mass matrix: Allowed ranges and implications of texture zeros

We study the range of the elements of the neutrino mass matrix

Broken mu-tau symmetry and leptonic CP violation

{m}_{\ensuremath{\nu}}

Deviations from tribimaximal neutrino mixing

in the charged lepton basis. Neutrinoless double beta decay is sensitive to the

Comparing trimaximal mixing and its variants with deviations from tri-bimaximal mixing

ee

Higgs →μτ in Abelian and non-Abelian flavor symmetry models

element (the effective mass) of

Unified parametrization for quark and lepton mixing angles

{m}_{\ensuremath{\nu}}