Theoretical Physics & Cosmology
Perseas
Christodoulidis
Postdoctoral Research Fellow
Department of Applied Mathematics and Theoretical Physics
University
of Cambridge
I am a theoretical cosmologist working on the physics of the early universe. My research centres on multi-field models of inflation, primordial non-Gaussianity, and the interplay between string theory and cosmological observables — in particular the implications of the Swampland programme for model-building.
Before Cambridge, I was a postdoc at the University of Geneva and completed my PhD at the University of Groningen under supervision of Diederik Roest.
Research
Multi-field Inflation
Inflationary trajectories with multiple active scalar fields — turning geodesics, non-adiabatic perturbations, and the effective single-field reduction. Understanding when and how turns in field space leave observable imprints.
Primordial Non-Gaussianity
Shape and amplitude of higher-order correlators as probes of the inflationary mechanism. Current Planck bounds and forecasts for upcoming CMB-S4, Simons Observatory, and LSS surveys.
Swampland & String Landscape
Implications of the de Sitter conjecture, distance conjecture, and the Trans-Planckian Censorship Conjecture for viable inflationary model-building. Tension between the Swampland and observational requirements.
Gravitational Waves
Stochastic gravitational-wave backgrounds generated by first-order phase transitions and by spectator fields during inflation. Detectability prospects for LISA, Einstein Telescope, and pulsar timing arrays.
Attractor Inflation
α-attractor models, Higgs inflation, and their generalisations. Universality in the CMB spectral index and tensor-to-scalar ratio at large N. Geometric origin of the attractor behaviour.
Reheating & Preheating
Transfer of energy from the inflaton sector to radiation. Parametric resonance, tachyonic preheating, and gauge preheating. Effects of the reheating epoch on the mapping between e-folds and observational scales.
Papers
All on INSPIREInflation & Early Universe
Geodesic and non-geodesic motion in multi-field inflation: sharp turns and the power spectrum
P. Christodoulidis, D. Roest, E. I. Sfard ·JCAP 08 (2024) 006
Angular inflation in multi-field α-attractors
P. Christodoulidis, D. Roest, E. I. Sfard · JCAP 11 (2023) 027
Scaling attractors in multi-field inflation
P. Christodoulidis, D. Roest, E. I. Sfard · JCAP 12 (2022) 022
Non-Gaussianity from geometrical destabilisation of inflation
P. Christodoulidis, D. Roest · Phys. Rev. D 107 (2023) 103503
Attractors, bifurcations and curvature in multi-field inflation
P. Christodoulidis, D. Roest, E. I. Sfard · JCAP 08 (2021) 006
Many-field inflation: universality and its limits
P. Christodoulidis, D. Roest, E. I. Sfard · JCAP 04 (2020) 030
Swampland & String Cosmology
Swampland conjectures and the inflationary landscape
P. Christodoulidis, A. Kehagias · JHEP 06 (2023) 092
de Sitter, Trans-Planckian censorship and α-attractors
P. Christodoulidis · Phys. Rev. D 105 (2022) 063519
Teaching
Advanced Cosmology
University of Cambridge
Inflation, dark energy, large-scale structure, and the CMB power spectrum. Problem sets and example sheets available below.
General Relativity
University of Cambridge
Differential geometry, Einstein's field equations, black holes, gravitational waves, and cosmological solutions.
Classical Mechanics
University of Groningen
Newtonian and Lagrangian mechanics, small oscillations, rigid body motion. Teaching assistant.
Electrodynamics
University of Groningen
Maxwell's equations, electromagnetic waves, radiation, and special relativity. Teaching assistant.
Talks
Sharp turns in multi-field inflation: observational signatures
Inflation and the CMB·Perimeter Institute, Waterloo
Non-Gaussianity from turning trajectories
Planck 2024 Conference·Paris, France
Geodesic and non-geodesic inflation: a unified framework
Cosmology from Home·Online
Swampland constraints and multi-field inflation
String Phenomenology 2024·Vienna, Austria
Gravitational waves from preheating with turns
LISA Cosmology Working Group·ESA, Noordwijk
Angular inflation in α-attractor models
Spanish Relativity Meeting·Valencia, Spain
Many-field inflation: universality and its limits
Inflation: Theory and Observations·KITP, Santa Barbara
Multi-field inflation on the Riemann surface
Amsterdam String Theory Workshop·Amsterdam, Netherlands