Inflationary dynamics in the braneworld scenarios

摘要

We analyze the attractor behaviour of the inflation field in braneworld scenarios using the Hamilton-Jacobi formalism,where the Friedmann equation has the form of H2 =ρ + ε√2ρ0ρ or H2 =ρ + ερ2/2σ,with ε =+ 1.We find that in all models the linear homogeneous perturbation can decay exponentially as the scalar field rolls down its potential.However,in the case of a-ρ2 correction to the standard cosmology with ρ ＜ σ,the existence of an attractor solution requires (σ-ρ)/φ2 ＞ 1.Our results show that the perturbation decays more quickly in models with positive-energy correction than in the standard cosmology,which is opposite to the case of negative-energy correction.Thus,the positive-energy modification rather than the negative one can assist the inflation and widen the range of initial conditions.