Ricci curvature non-minimal derivative coupling cosmology with field re-scaling
In this letter, cosmology of a simple NMDC gravity with $ξR ϕ_{,μ}ϕ^{,μ}$ term and a free kinetic term is considered in flat geometry and in presence of dust matter. A logarithm field transformation $ϕ' = μ\ln ϕ$ is proposed phenomenologically. Assuming slow-roll approximation, equation of motion, scalar field solution and potential are derived as function of kinematic variables. The field solution and potential are found straightforwardly for power-law, de-Sitter and super-acceleration expansions. Slow-roll parameters and slow-roll condition are found to depend on more than one variable. At large field the re-scaling effect can enhance the acceleration. For slow-rolling field, the negative coupling $ξ$ could enhance the effect of acceleration.