10 research outputs found
Cosmological model with non-minimally coupled fermionic field
A model for the Universe is proposed whose constituents are: (a) a dark
energy field modeled by a fermionic field non-minimally coupled with the
gravitational field, (b) a matter field which consists of pressureless baryonic
and dark matter fields and (c) a field which represents the radiation and the
neutrinos. The coupled system of Dirac's equations and Einstein field equations
is solved numerically by considering a spatially flat homogeneous and isotropic
Universe. It is shown that the proposed model can reproduce the expected
red-shift behaviors of the deceleration parameter, of the density parameters of
each constituent and of the luminosity distance. Furthermore, for small values
of the red-shift the constant which couples the fermionic and gravitational
fields has a remarkable influence on the density and deceleration parameters.Comment: Accepted for publication in Europhysics Letter
Fermions in a Walecka-type cosmology
A simplified Walecka-type model is investigated in a cosmological scenario.
The model includes fermionic, scalar and vector fields as sources. It is shown
that their interactions, taking place in a Robertson-Walker metric, could be
responsible for the transition of accelerated-decelerated periods in the early
universe and a current accelerated regime. It is also discussed the role of the
fermionic field as the promoter of the accelerated regimes in the early and the
late stages of the universe.Comment: 8 pages, 4 figures. To appear in EP
Dark Energy Model with Spinor Matter and Its Quintom Scenario
A class of dynamical dark energy models, dubbed Spinor Quintom, can be
constructed by a spinor field with a nontraditional potential. We find
that, if choosing suitable potential, this model is able to allow the
equation-of-state to cross the cosmological constant boundary without
introducing any ghost fields. In a further investigation, we show that this
model is able to mimic a perfect fluid of Chaplygin gas with during
the evolution, and also realizes the Quintom scenario with its
equation-of-state across -1.Comment: 20 pages, 5 figures, accepted by CQG, several references adde
Fermionic cosmologies with Yukawa-type interactions
In this work we discuss if fermionic sources could be responsible for accelerated periods in a Friedmann-Robertson-Walker spatially flat universe, including a usual self-interaction potential of the Nambu-Jona-Lasinio type together with a fermion-scalar interaction potential of the Yukawa type. The results show that the combination of these potentials could promote an initially accelerated period, going through a middle decelerated era, with a final eternal accelerated period, where the self-interaction contribution dominates