  These lectures cover aspects of primordial cosmology with a focus on
observational tests of physics beyond the Standard Model. The presentation is
divided into two parts: In Part I, we study the production of new light
particles in the hot big bang and describe their effects on the anisotropies of
the cosmic microwave background. In Part II, we investigate the possibility of
very massive particles being created during inflation and determine their
imprints in higher-order cosmological correlations.
