ICTS

During inflation, the quantum fluctuations at the epoch are magnified into classical perturbations that leave an imprint as anisotropies in the cosmic microwave background (CMB). CMB observations show that the primordial perturbations are nearly scale-invariant, which imposes a condition that the canonical scalar field potential needs to be almost flat. However, in the standard model of particle physics, there is no natural candidate with such flat potentials that could sustain inflation. The focus of our work was to address this issue. More specifically, inflation is realised in three different modified gravity models. First, we show that inflation could be realised in Gauss-Bonnet gravity, with the Higgs scalar non-minimally coupled to the Gauss-Bonnet term. Second, in Jordan frame, we show that a massive scalar field can drive inflation, where gravity is modified in a way closely resembling scalar-tensor theories of gravity. Finally, we consider a modified gravity model of exponential non-minimal coupling.