Fermions as sources of accelerated regimes in cosmology

In this work it is investigated if fermionic sources could be responsible for accelerated periods during the evolution of a universe where a matter field would answer for the decelerated period. The self-interaction potential of the fermionic field is considered as a function of the scalar and pseudoscalar invariants. Irreversible processes of energy transfer between the matter and gravitational fields are also considered. It is shown that the fermionic field could behave like an inflaton field in the early universe and as dark energy for an old universe.

Figure 1

Acceleration field $\ddot{a}$ vs time $t$.

Figure 2

Energy densities of fermionic ${\rho }_f$ and matter ${\rho }_m$ fields vs time $t$.

Figure 3

Acceleration field $\ddot{a}$ vs time $t$. Dashed line: $\alpha =0.1$; straight line: $\alpha =0.05$; dotted line: without irreversible processes.

Figure 4

Energy densities of fermionic ${\rho }_f$ and matter ${\rho }_m$ fields vs time $t$. Dotted and dotted-dashed lines: without irreversible processes; straight and dashed lines: $\alpha =0.1$.