Perseas
Christodoulidis

How can dissipation and noise be incorporated consistently into gauge theories, gravity, and inflation? The Schwinger-Keldysh formalism provides the natural language for open systems, where energy and information leak into sectors we do not observe.

What imprints does inflationary dynamics leave in the data? Large turns can amplify the curvature power spectrum — with consequences for primordial black holes and scalar-induced gravitational waves — while new shapes of primordial non-Gaussianity emerge, such as scalar-tensor cross-bispectra in parity-violating Chern-Simons gravity.

How can we construct inflationary models in the presence of many interacting scalar fields, as suggested by high-energy embeddings of the theory? Turning (or non-geodesic) trajectories, naturally emerging in curved field-space geometries, alter both the background evolution and the perturbations, opening qualitatively new dynamics beyond the single-field paradigm. Classifying the late-time attractors of these models: scaling solutions, rapid-turn attractors, and non-minimally coupled attractors. Understanding when inflationary predictions become universal — insensitive to initial conditions, priors, and the number of fields — and when they retain memory of them.

When can a multi-field cosmology be solved exactly? General solutions exist for N fields with exponential potentials and hyperbolic field spaces, providing benchmarks where the full dynamics is known analytically.