Localization of massless Elko spinor fields on de Sitter thick branes

In this work, we investigate the localization of a five-dimensional (5D) free massless Elko spinor field on de Sitter thick branes that are generated by a canonical or phantom scalar field. It is shown that the zero mode of Elko field cannot be localized on the de Sitter brane. In order to circumvent this problem, we employ a nonminimal coupling term in the 5D Elko spinor field action and find that the Elko field can be localized on the de Sitter brane with this mechanism.

Classification of singular spinor fields and other mass dimension one fermions

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.

ELKO SPINOR FIELDS AS A TOOL FOR PROBING EXOTIC TOPOLOGICAL SPACETIME FEATURES

We report about some achievements and developments provided by the ELKO program, in particular the ones recently accomplished.1 Exotic dark spinor fields has been investigated in the context of inequivalent spin structures on arbitrary curved spacetimes, which induces an additional term on the associated Dirac operator, related to a Čech cohomology class. Exotic terms operating on standard model Dirac spinor fields are usually absorbed by gauge transformations encoded as a shift of some vector potential representing an element of the cohomology group H1(M, ℤ2). That is not the case of ELKO, once they cannot carry gauge charge. As a consequence, the ELKO program requires a complete evaluation of topological analysis. Since exotic dark spinor fields also satisfy Klein-Gordon propagators, the dynamical constraints related to the exotic term in the Dirac equation can be explicitly computed. It forthwith implies that the non-trivial topology associated to the spacetime can drastically engender — from the dynamics of dark spinor fields — constraints on the spacetime metric structure. Besides being candidates to the dark matter problem, dark spinor fields are shown to be potential candidates to probe non-trivial topologies in spacetime, as well as to explain the spacetime metric structure.

FROM DIRAC ACTION TO ELKO ACTION

A fundamental action, representing a mass dimension-transmuting operator between Dirac and ELKO spinor fields, is performed on the Dirac Lagrangian, in order to lead it into the ELKO Lagrangian. Such a dynamical transformation can be seen as a natural extension of the Standard Model that incorporates dark matter fields. The action of the mass dimension-transmuting operator on a Dirac spinor field, that defines and introduces such a mapping, is shown to be a composition of the Dirac operator and the nonunitary transformation that maps Dirac spinor fields into ELKO spinor fields, defined in J. Math. Phys.48, 123517 (2007). This paper gives allowance for ELKO, as a candidate to describe dark matter, to be incorporated in the Standard Model. It is intended to present for the first time, up to our knowledge, the dynamical character of a mapping between Dirac and ELKO spinor fields, transmuting the mass dimension of spin one-half fermionic fields from 3/2 to 1 and from 1 to 3/2.