Gauss-Bonnet Inflation after Planck2018
  We study the primordial perturbations and reheating process in the models
where the Gauss-Bonnet term is non-minimally coupled to the canonical and
non-canonical (DBI and tachyon) scalar fields. We consider several potentials
and Gauss-Bonnet coupling terms as power-law, dilaton-like, $\cosh$-type,
E-model and T-model. To seek the observational viability of these models, we
study the scalar perturbations numerically and compare the results with the
Planck2018 TT, TE, EE+lowE+lensing+BK14+BAO joint data at $68\%$ CL and $95\%$
CL. We also study the tensor perturbations in confrontation with the Planck2018
TT, TE, EE+lowE+lensing+BK14+BAO+ LIGO$\&$Virgo2016 joint data at $68\%$ CL and
$95\%$ CL. In this regard, we obtain some constraints on the Gauss-Bonnet
coupling parameter $\beta$. Another important process in the early universe is
the reheating phase after inflation which is necessary to reheat the universe
for subsequent evolution. In this regard, we study the reheating process in
these models and find some expressions for the e-folds number and temperature
during that era. Considering that from Planck TT,TE,EE+lowEB+lensing data and
BICEP2/Keck Array 2014, based on the $\Lambda$CDM$+r+\frac{dn_{s}}{d\ln k}$
model, we have $n_{s}=0.9658\pm 0.0038$ and $r<0.072$, we obtain some
constraints on the e-folds number and temperature. From the values of the
e-folds number and the effective equation of state and also the observationally
viable value of the scalar spectral index, we explore the capability of the
models in explaining the reheating phase.
