International Journal of Modern Physics D

We review how Elko arise as an extension of complex-valued four-component Majorana spinors. This is followed by a discussion that constrains certain elements of phase freedom. A proof is reviewed that unambiguously establishes that Elko, and for that matter the indicated Majorana spinors, cannot satisfy Dirac equation. They, however do, as they must, satisfy spinorial Klein–Gordon equation. We then introduce a quantum field with Elko as its expansion coefficients and show that it is causal, satisfies Fermi statistics, and then refer to the existing literature to remind that its mass dimension is one. We conclude by providing an up-to-date bibliography on the subject.

In this paper, the recently-introduced ELKO and the well-known Dirac spinor fields will be compared. However, instead of comparing them under the point of view of their algebraic properties or their dynamical features, we will proceed by investigating the analogies and similarities in terms of their geometrical character viewed from the perspective of torsion. The paper will be concluded by sketching some consequences for the application to cosmology and particle physics.

In this paper, we investigate the constraint equations of the Lounesto spinor fields classification and show that it can be used to completely characterize all the singular classes, which can potentially accommodate further mass dimension one fermions, beyond the well known Elko spinor fields. This result can be useful for two purposes: Besides a great abridgement in the classification of a given spinor field, we provide a general form of each class of spinor fields, which can be used furthermore to search for a general classification of spinors dynamics.

In this paper, we provide a new derivation of the Dirac equation which promptly generalizes to higher spins. We apply this idea to spin-half Elko dark matter.

We discuss the coupling of fermionic fields with mass dimension one to the O'Raifeartaigh model to study supersymmetry breaking for these fermions. We find that the coupled model has two distinct solutions. The first solution represents a local minimum of the superpotential which spontaneously breaks supersymmetry in perfect analogy to the O'Raifeartaigh model. The second solution is more intriguing as it corresponds to a global minimum of the superpotential. In this case, the coupling to the fermionic sector restores supersymmetry. However, this is achieved at the cost of breaking Lorentz invariance. Finally, the mass matrices for the multiplets of the coupled model are presented. It turns out that it contains two bosonic triplets and one fermionic doublet which are mass multiplets. In addition, it contains a massless fermionic doublet as well as one fermionic triplet which is not a mass multiplet but rather an interaction multiplet that contains component fields of different mass dimension.

The results also imply that the presented model for fermionic fields with mass dimension one is an interesting candidate for supersymmetric dark matter (DM).

The aim of this work is to explore the possibility to discover a fermionic field with mass dimension one, the Elko field, in the 14 TeV Large Hadron Collider (LHC), in processes with missing energy and one jet. We explore the possibility of a triple coupling with the Higgs field, generating also a contribution to the Elko mass term, and suggest some possibilities for future studies in this field.

In this paper, we consider dark spinor and Higgs fields coupled to gravity and calculate their contributions to the energy density and pressure in Friedmann–Robertson–Walker spacetime. We seek solutions of the fields to yield a de Sitter universe and investigate stability properties of the solutions using linear approximation. We discuss the possibility that the inflationary period of our universe can be described by a combination of the dark spinor and Higgs fields.

Generalized Dirac equation with operator mass term is presented. Its solutions are nonstandard spinors (NSS) which, like eigenspinoren des Ladungskonjugationsoperators (ELKO), are eigenvectors of the charge conjugation and dual-helicity operators. It is demonstrated that in spite of their noncovariant nature the NSS can serve as a carrier space of a representation of Poincaré group. However, the corresponding boost generators are not manifestly covariant and generate nonlocal momentum dependent transformations, which are presented explicitly. These results can present a new look on group-theoretical grounds of ELKO theories.

A brief review is presented about the ELKO spinor field applied to cosmology, with the main results and limitations of the theory. As a simple application, we have analyzed a model involving the interaction of the ELKO spinor field with dark matter in the universe from a dynamical system approach. When the system is rewritten in terms of the deceleration parameter q and under the assumption that such parameter is nearly constant for some different stages of the evolution, stability points were found for different types of interaction between dark matter and ELKO spinors. Within this new analysis several interesting scenarios are possible, depending on the interaction term. For example, if it is assumed that the equation of the state parameter of the ELKO field is of the phantom type, ω_ϕ < -1, the current acceleration of the universe can be driven by the decay of dark matter particles into ELKO field. Furthermore, even for ω_ϕ > 0, the inflationary period can be driven by the decay of the inflaton field (described by the ELKO spinor) into dark matter particles.

Ettore Majorana was the brightest Italian theoretical physicist of the XX century (actually, Enrico Fermi regarded him as the brightest in the world of his time, and compared him to Galileo and Newton), even if to some people Majorana is often known mainly for his mysterious disappearance, in 1938, when he was 31. In this paper, we present a panoramic view of the main scientific articles published by him, as well as their significance. We also briefly outline his life, the biographical data being based on letters, documents, testimonies discovered or collected by the author during more than four decades, and contained since 1986 in Recami's book quoted in the text. Finally, extensive information and comments are added with regard to the scientific manuscripts left unpublished by Majorana. Two pictures complete the paper.