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In this work, the Friedman equations for hadronic matter in the Robertson-Walker metric in the early Universe are obtained. We consider the hadronic phase, formed after the hadronization of the quark-gluon plasma, that means times from 10^{-6}s to 1s. The set of equations is derived and the behavior of the system is studied considering one approximate analytical solution.
Upon applying Chamseddines noncommutative deformation of gravity we obtain the leading order noncommutative corrections to the Robertson-Walker metric tensor. We get an isotropic inhomogeneous metric tensor for a certain choice of the noncommutativit
All possible transformations from the Robertson-Walker metric to those conformal to the Lorentz-Minkowski form are derived. It is demonstrated that the commonly known family of transformations and associated conformal factors are not exhaustive and t
The thermal decoupling description of dark matter (DM) and co-annihilating partners is reconsidered. If DM is realized at around the TeV-mass region or above, even the heaviest electroweak force carriers could act as long-range forces, leading to the
We completely classify Friedmann-Lema^{i}tre-Robertson-Walker solutions with spatial curvature $K=0,pm 1$ and equation of state $p=wrho$, according to their conformal structure, singularities and trapping horizons. We do not assume any energy conditi
The cosmological evolution can modify the dark matter (DM) properties in the early Universe to be vastly different from the properties today. Therefore, the relation between the relic abundance and the DM constraints today needs to be revisited. We p