Constraining Inflation with the CMB: From Cosmological Colliders to Open Quantum Systems

Petar Suman explores how higher-order statistics of the cosmic microwave background connect inflationary theory to observations. Although single-field inflation explains the origin of primordial fluctuations, its particle-physics mechanism remains uncertain. The first part examines the cosmological-collider programme: massive fields during inflation can leave oscillatory signatures in primordial non-Gaussianity, allowing measurements to constrain the masses and spins of early-universe particles. The second treats inflation as an open quantum system. An open effective field theory describes dissipation produced when the inflaton interacts with an environmental bath; joint analysis of the CMB power spectrum and bispectrum can then constrain those dynamics. Together, these approaches use precise cosmological data to test complex inflationary models at energies inaccessible to terrestrial accelerators.