Theoretical physics: dark matter and cosmology
I'm a PhD student at Queen's University and a visiting researcher at Heidelberg University. I work on dark matter and cosmology, including composite dark matter and its imprint on the early universe, and axions.
Guides for students
All guides →Bachelor's in Leipzig (IPSP)
Master's at Heidelberg
PhD applications
Composite Dark Matter, Part II: The Leftover Scalar Field
2026-08-26
When dark matter forms large composites, the binding energy has to go somewhere. In a secluded dark sector it goes into the light scalar field, which can leave a trace in the CMB.
3036 words
|
15 minutes
Composite Dark Matter, Part I: From Dark Atoms to Dark Nuggets
2026-08-25
Most of the matter we know is made of bound states. Could dark matter be too? From dark atoms up to very heavy dark nuggets, and how you would detect them.
2938 words
|
15 minutes
Furry's Theorem, Part 1: The Proof
2026-07-25
Proving Furry's theorem (correlation functions with an odd number of photon fields vanish) with the path integral and with Feynman diagrams.
2104 words
|
11 minutes
Furry's Theorem, Part 2: Consequences and Exceptions
2026-07-25
What Furry's theorem implies: no photon tadpole, no three-photon vertex, only even powers of F in Euler-Heisenberg, light-by-light scattering only at fourth order, and where the theorem fails.
1192 words
|
6 minutes
Self-Energy, 1PI Diagrams, and the Dyson Resummation
2026-05-02
How perturbation theory computes the field strength renormalization Z and the shift from bare to physical mass, by resumming 1PI insertions into the full propagator.
1272 words
|
6 minutes
The Källén–Lehmann Spectral Representation and Why We Renormalize
2026-05-01
A non-perturbative argument that the interacting two-point function forces a field strength renormalization Z and a physical mass different from the bare mass, before any loop is computed.
1863 words
|
9 minutes
Starting MSc Physics at Heidelberg — What We Wish We Knew Earlier
2026-04-15
Notes to go with the video I made with STARGAZER on starting the M.Sc. Physics at Heidelberg: courses, the oral exam, research groups, admin and life in the city.
2519 words
|
13 minutes
Lie Groups and Lie Algebras, Part IV: The Poincaré Group and the Classification of Particles
2026-04-06
The Poincaré group, its two Casimir operators, and Wigner's classification of particles by mass and spin or helicity.
2955 words
|
15 minutes