First and second order cosmological perturbations in light mass Galileon models
AbstractIn this paper, we investigate the first and second order cosmological perturbations in the light mass Galileon (LMG) scenario. LMG action includes the cubic Galileon term along with the standard kinetic term and a potential that is added phenomenologically to achieve late time acceleration. The scalar field is nonminimally coupled to matter in the Einstein frame. Integral solutions of growing and decaying modes are obtained. The effect of the conformal coupling constant (β), at the perturbation level, has been studied. In this regard, we have studied the linear power spectrum and bispectrum. Though different values of β have different effects on the power spectrum on the reduced bispectrum the effect is not significant. It has been found that the redshift-space distortions data can be very useful to constrain β. In this study we consider potentials that can lead to tracker behavior of the scalar field.