Light Inflaton -- hunting for it from CMB through the Dark Matter and down to the colliders

<!--HTML-->The models without additional energy scales (heavy particles) above the electroweak scale can provide relation between the low energy physics and cosmology. Probably the simplest example is the model with additional singlet scalar inflaton (with non-minimal coupling). It gets constraint simultaneously from the inflationary observations (tensor modes), dark matter production (for 7keV sterile neutrino DM), and searches in the reare decays. I will discuss the interplay of the cosmological and laboratory constraints in this model.