A bstract We investigate the impact of new light particles, carrying significant energy in the
early universe after neutrino decoupling, on the cosmological effective relativistic neutrino …

The basic idea of this work is to achieve the observed relic density of a non-thermal dark
matter (DM) and its connection with Cosmic Microwave Background (CMB) via additional …

The presence of any extra radiation energy density at the time of cosmic microwave
background formation can significantly impact the measurement of the effective relativistic …

The existence of prolonged radiation domination prior to the Big Bang Nucleosynthesis
(BBN), starting just after the inflationary epoch, is not yet established unanimously. If instead …

The current upper limit on $ N_ {\rm eff} $ at the time of CMB by Planck 2018 can place
stringent constraints in the parameter space of BSM paradigms where their additional …