# Evolution of the universe driven by a mass dimension one fermion field

## TL;DR

This paper investigates how a mass dimension one fermion field, called Elko, can drive the universe's evolution, including inflation, dark matter, and acceleration, with results aligning with standard cosmological estimates.

## Contribution

It introduces a cosmological model driven by Elko fermions, demonstrating their role in inflation, dark matter, and acceleration, with consistent energy density evolution and a new upper mass limit.

## Key findings

- Reproduces inflationary phase with Elko field dynamics.
- Aligns energy densities at key cosmological epochs with standard model.
- Establishes an upper mass limit for Elko field at 10^9 GeV.

## Abstract

This paper study the evolution of the universe filled with a neutral mass dimension one fermionic field, sometimes called Elko. The numerical analysis of the coupled system of equations furnish a scale factor growth and energy density evolution that correctly reproduces the inflationary phase of the universe. After that, supposing a mechanism of energy transference to ordinary matter, the initial conditions generated after inflation drives the radiation dominated phase and also the subsequent dark matter evolution, since the Elko field is a good dark matter candidate. The energy density of the field at the end of inflation, at the end of radiation phase and for present time are in agreement to the standard model estimates. The analysis was performed with a potential containing a quadratic mass term plus a quartic self-interaction term, which follows naturally from the theory of mass dimension one fermions. It is interesting to notice that inflation occurs when the field makes a kind of transition around the Planck mass scale. The number of e-foldings during inflation was found to be strongly dependent on the initial conditions of the Elko field, as occurs in chaotic inflationary models. An upper mass limit for Elko field has been obtained as $m<10^9$GeV. A possible interpretation of both inflationary phase and recent cosmic acceleration as a consequence of a kind of Pauli exclusion principle is presented at the end.