We study gravitational wave production in an expanding Universe during the first stages following inflation, and investigate the consequences of the Gauss-Bonnet term on the inflationary parameters for a power-law inflation model with a GB coupling term. Moreover, we perform the analyses on the preheating parameters involving the number of e-folds $N_{ pre}$, and the temperature of thermalization $T_{ th},$ and show that it's sensitive to the parameters $n$, and $\gamma$, the parameter $\gamma$ is proposed to connect the density energy at the end of inflation to the preheating energy density. We set a correlation of gravitational wave energy density spectrum with the spectral index $n_{ s}$ detected by the cosmic microwave background experiments$.$ The density spectrum $\Omega_{ gw}$ shows good consistency with observation for $\gamma = 10^{ 3}$ and $10^{ 6}$. Our findings suggest that the generation of gravitational waves (GWs) during preheating can satisfy the constraints from Planck's data.
Categories: gr-qc hep-th