In the age of precision cosmology, the LambdaCDM model precisely fits most cosmological observations; however, discrepancies have been reported in measuring a local Hubble parameter at low and high redshifts. One possible way to reduce Hubble tension is by allowing dark sectors to interact. Historically, this has been accomplished by incorporating the interaction term at the covariant...
We study the imprints of high scale non-thermal leptogenesis on cosmic microwave background (CMB) from the measurements of inflationary spectral index ($n_s$) and tensor-to-scalar ratio ($r$), which otherwise is inaccessible to the conventional laboratory experiments. We argue that non-thermal production of baryon (lepton) asymmetry from subsequent decays of inflaton to heavy right-handed...
We propose a new class of f(R) theory where its Weyl gauge symmetry is broken in the primordial era of the universe. Due to the geometrical nature of the symmetry, the symmetry breaking induces an additional non-minimal coupling of the scalar field corresponding to the f(R) model. This cannot be expected in the standard f (R) theories. We explain how this affects the evolution of the universe...
In this work, the Rastall model of gravity is generalized different models of non-conserve mater energy momentum model of gravity is constructed. In fact, we show that by imposing the ordinary or generalized form of Rastall assumption on perfect fluid energy-momentum tensor (EMT), one can find different {\bf {forms}} of modified Einstein's field equation (EFE). We investigate the...
