MiniBooNE and a (CP)^2 = -1 sterile neutrino

It has been taken as granted that the observation of two independent mass-squared differences necessarily fixes the number of underlying mass eigenstates as three, and that the addition of a sterile neutrino provides an additional mass-squared difference. The purpose of this Letter is to argue that if one considers a sterile neutrino component that belongs to the (CP)^2 = - 1 sector, then both of the stated claims are false. We also outline how the results reported here, when combined with the forthcoming MiniBooNE data and other experiments, can help settle the issue of the CP properties of the sterile neutrino; if such a component does indeed exist.Comment: Mod. Phys. Lett. A (in press, 8 pages

Dynamical dispersion relation for ELKO dark spinor fields

An intrinsic mass generation mechanism for exotic ELKO dark matter fields is scrutinized, in the context of the very special relativity (VSR). Our results are reported on unraveling inequivalent spin structures that educe an additional term on the associated Dirac operator. Contrary to the spinor fields of mass dimension 3/2, this term is precluded to be absorbed as a shift of some gauge vector potential, regarding the equations for the dark spinor fields. It leads to some dynamical constraints that can be intrinsically converted into a dark spinor mass generation mechanism, with the encoded symmetries maintained by the VSR. The dynamical mass is embedded in the VSR framework through a natural coupling to the kink solution of a \lambda \phi^{4} theory for a scalar field \phi. Our results evince the possibility of novel effective scenarios, derived from exotic couplings among dark spinor fields and scalar field topological solutions.Comment: 6 pages, to appear in Phys.Lett.

Discrete quantum gravity: a mechanism for selecting the value of fundamental constants

Smolin has put forward the proposal that the universe fine tunes the values of its physical constants through a Darwinian selection process. Every time a black hole forms, a new universe is developed inside it that has different values for its physical constants from the ones in its progenitor. The most likely universe is the one which maximizes the number of black holes. Here we present a concrete quantum gravity calculation based on a recently proposed consistent discretization of the Einstein equations that shows that fundamental physical constants change in a random fashion when tunneling through a singularity.Comment: 5 pages, RevTex, 4 figures, honorable mention in the 2003 Gravity Research Foundation Essays, to appear in Int. J. Mod. Phys.

Exotic Low Density Fermion States in the Two Measures Field Theory: Neutrino Dark Energy

We study a new field theory effect in the cosmological context in the Two Measures Field Theory (TMT). TMT is an alternative gravity and matter field theory where the gravitational interaction of fermionic matter is reduced to that of General Relativity when the energy density of the fermion matter is much larger than the dark energy density. In this case also the 5-th force problem is solved automatically. In the opposite limit, where the magnitudes of fermionic energy density and scalar field dark energy density become comparable, nonrelativistic fermions can participate in the cosmological expansion in a very unusual manner. Some of the features of such states in a toy model of the late time universe filled with homogeneous scalar field and uniformly distributed nonrelativistic neutrinos: neutrino mass increases as m ~ a^{3/2}; the neutrino gas equation-of-state approaches w=-1, i.e. neutrinos behave as a sort of dark energy; the total (scalar field + neutrino) equation-of-state also approaches w=-1; the total energy density of such universe is less than it would be in the universe filled with the scalar field alone. An analytic solution is presented. A domain structure of the dark energy seems to be possible. We speculate that decays of the CLEP state neutrinos may be both an origin of cosmic rays and responsible for a late super-acceleration of the universe. In this sense the CLEP states exhibit simultaneously new physics at very low densities and for very high particle masses.Comment: 47 pages, accepted for publication in Int.J.Mod.Phys.