Early Inflationary Phase with Canonical and Noncanonical Scalar Fields: A Symmetry-Based Approach

摘要: We study the early inflationary phase of universe driven by noncanonical scalar field models using an exponential potential. The are represented Lagrangian densities containing square and square-root kinetic corrections to canonical density. investigate Lie symmetry homogeneous equations obtained from find only a one-parameter point for both equations. use generator obtain exact analytical group-invariant solution invariant curve condition. solutions consistent satisfy Friedmann subject constraint conditions on potential parameter $$\lambda$$ case $$\mu$$ case. In this scenario, we values various parameters make useful checks observational constraints Planck data imposing set bounds . results spectral index ( $$n_{S}$$ ) tensor-to-scalar ratio $$r$$ presented in $$(n_{S},r)$$ plane background Planck-2015 Planck-2018 cases good agreement with cosmological observations. For theoretical completeness models, verify that under consideration free ghosts Laplacian instabilities. also treat model two power-law (kinetic) dynamical system theory. provide stability critical points show inflation stable attractors space.