Naturalness and stability of the generalized Chaplygin gas in the seesaw cosmon scenario

Author(s)

Bernardini, A. E. ^{[1, 2]} ; Bertolami, O. ^{[3, 2]}

Affiliation

^[1] Univ Fed Sao Carlos, Dept Fis, BR-13565905 Sao Carlos, SP - Brazil

^[2] Inst Super Tecn, Dept Fis, P-1049001 Lisbon - Portugal

^[3] Inst Super Tecn, Inst Plasmas & Fusao Nucl, P-1049001 Lisbon - Portugal

• Document type: Journal article
• Source: Physical Review D; v. 81, n. 12, p. 123013, 2010.
• Web of Science Citations: 7

Abstract

The seesaw mechanism is conceived on the basis that a mass scale, xi, and a dimensionless scale, s, can be fine-tuned in order to control the dynamics of active and sterile neutrinos through cosmon-type equations of motion: the seesaw cosmon equations. This allows for sterile neutrinos to be a dark matter candidate. In this scenario, the dynamical masses and energy densities of active and sterile neutrinos can be consistently embedded into the generalized Chaplygin gas (GCG), the unified dark sector model. In addition, dark matter adiabatically coupled to dark energy allows for a natural decoupling of the (active) mass varying neutrino component from the dark sector. Thus mass varying neutrinos turn into a secondary effect. Through the scale parameters, xi and s, the proposed scenario allows for a convergence among three distinct frameworks: the cosmon scenario, the seesaw mechanism for mass generation, and the GCG model. It is found that the equation of state of the perturbations is the very one of the GCG background cosmology so that all the results from this approach are maintained, being smoothly modified by active neutrinos. Constrained by the seesaw relations, it is shown that the mass varying mechanism is responsible for the stability against linear perturbations and is indirectly related to the late time cosmological acceleration. (AU)