Research Projects

The inflationary scenario is a promising paradigm for describing primordial perturbations in the early universe. The simplest slow-roll inflationary models, which typically have one dynamical degree of freedom, are consistent with observations of the Cosmic Microwave Background (CMB) and the Large Scale Structure. The inflaton, a slowly rolling scalar field, dominates the total energy density of the universe and generates scale-invariant spectra of scalar and metric tensor fluctuations. Recent CMB observations from Planck favor small field inflationary models, but many large field models have been strongly ruled out. Slow-roll inflationary models with a suitable small tensor-to-scalar ratio seem to be consistent with data at the level of power spectra and bispectra. Preliminary gauge fields may also be present during inflation, but their dynamics can be ignored if not strongly excited due to weak gravitational coupling. However, if gauge fields are dynamically evolving due to strong couplings, their contribution to inflationary observables should be consistently considered for calculating cosmological observables. These dynamical gauge fields are correlated with scalar and tensor fluctuations, causing novel non-Gaussian imprints in the CMB. They also induce non-vanishing anisotropic stresses, which can source a secondary contribution to gravitational waves (GW) generated during inflation. The project aims to investigate higher order non-Gaussian cross-correlations of primordial gauge fields with scalar and tensor perturbations in parity conserving and parity violating scenarios and calculate the induced GWs contributions due to anisotropic stresses in both kinetic and helical coupling scenarios.

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