It is hard to understand spin-one-half fields without reading Weinberg. This paper is a pedagogical footnote to his formalism with an emphasis on the boost matrix, spinors, and Majorana fields. Learning about Majorana and Dirac Fields 2

In this letter in the framework of a simple see-saw scenario with two (or three) quasi degenerate Majorana neutrinos we propose that one of these neutrinos can be very weakly coupled, yet there is a mechanism of the generation of the abundance of such ”dark” neutrino in the early universe. The mechanism of production is due to oscillations between ”dark” Majorana neutrino and one of the Majoran...

Assuming 3-ν mixing and massive Majorana neutrinos, we present some implications of the oscillation solutions of the solar and atmospheric neutrino problems and of the results of the CHOOZ experiment for the predictions of the effective Majorana mass in neutrinoless double beta-decay. If the present or upcoming (ββ)0ν -decay searches give a positive result, the Majorana nature of massive neutri...

We prove a general low-energy theorem establishing a generic relation between the neutrino Majorana mass and the superpartner sneu-trino B-L-violating " Majorana "-like mass term. The theorem states that, if one of these two quantities is non-zero the other one is also non-zero and, vice versa, if one of them vanishes the other vanishes, too. The theorem is a consequence of the underlying super...

We propose a simple but suggestive seesaw model with two phenomenological conjectures: three heavy (right-handed) Majorana neutrinos are degenerate in mass in the symmetry limit and three light Majorana neutrinos have the tribimaximal mixing pattern V0. We show that a small mass splitting between the first generation and the other two generations of heavy Majorana neutrinos is responsible for t...

Zero-energy Majorana bound states in superconductors have been proposed to be potential building blocks of a topological quantum computer, because quantum information can be encoded nonlocally in the fermion occupation of a pair of spatially separated Majorana bound states. However, despite intensive efforts, nonlocal signatures of Majorana bound states have not been found in charge transport. ...

The existence of three generations of neutrinos and their mass mixing are the deep mysteries of our universe. The history of neutrino physics can be traced back to Majorana’s elegant work on a real solution of the Dirac equation – known as the Majorana fermion. A cutting-edge step towards understanding the nature of neutrino has been taken by the experimental discovery of neutrino mass mixing d...

In 1932 Ettore Majorana proposed an infinite-component relativistic wave equation for particles of arbitrary integer and half-integer spin. In the late 80s and early 90s it was found that the higher-derivative geometric particle models underlie the Majorana equation, and that its (2+1)dimensional analogue provides with a natural basis for the description of relativistic anyons. We review these ...

The rare kaon decay K+ → π−μ+μ+ is violating lepton number by two units and is investigated within the context of Majorana neutrino masses. Using a new upper bound from E865 an upper limit on the effective Majorana mass term 〈mμμ〉 < ∼ 500 GeV could be obtained. This is improving existing bounds by about one order of magnitude. Implications on heavy neutrinos are discussed as well as future poss...

We propose a method to coherently transfer quantum information, and to create entanglement, between topological qubits and conventional spin qubits. Our suggestion uses gated control to transfer an electron (spin qubit) between a quantum dot and edge Majorana modes in adjacent topological superconductors. Because of the spin polarization of the Majorana modes, the electron transfer translates s...