Hello there!
I'm Sebastian đź‘‹

Research Scientist at University of Regensburg  Â·  PhD in Theoretical Physics

I'm a theoretical physicist with a background in numerical simulations and statistical data analysis.
This is my personal page. You'll find projects, publications, and a bit about me below.

bio

  1. 2025 —

    Postdoctoral Researcher, Universität Regensburg

    I am currently working as a postdoctoral researcher in lattice QCD at the chair of Sara Collins.

  2. 2022 — 2025

    PhD in Theoretical Physics, Universität Regensburg

    I completed my PhD in lattice QCD under the supervision of Christoph Lehner. My main research focused on the muon anomalous magnetic moment (g-2): I computed the short-distance window of the leading-order hadronic vacuum polarization for the first time from first-principles lattice QCD. I carried out the project end-to-end, including HPC simulations, data pipeline design, and a lot of statistical analysis.

    The resulting estimate is cited in the 2025 Muon g-2 Theory Initiative White Paper and contributes to the current Standard Model prediction of the muon g-2.

    In parallel, I collaborated with Gunnar Bali and Sara Collins on precision charmonium spectroscopy.

    Towards the end of my PhD, I squeezed in an embedded software development internship at the start-up excav in Erlangen.

  3. 2018 — 2021

    M.Sc. in Physics, Universität Regensburg

    During my master's degree, I specialized in theoretical physics with a focus on lattice QCD and computational methods. My thesis with Christoph Lehner focused on algorithmic improvements for Markov Chain Monte Carlo simulations in lattice field theory (Schwinger model) on HPC systems.

    In addition, I worked as a student assistant at Bertrandt in their Advanced Driver Assistance Systems team in Regensburg.

  4. 2014 — 2018

    B.Sc. in Physics, Friedrich-Alexander Universität Erlangen-Nürnberg

    I did my bachelor's thesis with Thorsten GlĂĽsenkamp and Gisela Anton at ECAP, simulating novel particle detector geometries for the planned Gen2 expansion of the IceCube neutrino telescope at the South Pole.

projects

A selection of my projects. The full list is available on GitHub.

python · mcmc

statpy

Python toolkit targeted at Markov Chain Monte Carlo data analysis in the context of lattice QCD.
pytorch · gpt

shakespeare-transformer

Character-level GPT implementation in PyTorch from scratch. Trained on Shakespeare with KV caching to speed up inference.
docker · ai

docker-sandbox

Sandboxed Docker container for experimenting with AI coding assistants (Claude Code, OpenAI Codex).

tech stack

academic background

My research focuses on lattice quantum chromodynamics (lattice QCD) — a first-principles approach to the theory of the strong interaction. Discretizing spacetime turns an otherwise intractable problem into one you can attack with numerical simulations, high-performance computing, and a lot of statistics.

publications

Phys. Rev. D 2025

High-precision continuum limit study of the HVP short-distance window

Sebastian Spiegel, Christoph Lehner

Physical Review D 111, 114517 (2025)

This work contributed to the 2025 Muon g-2 Theory Initiative White Paper. Using supercomputers, we performed the first high-precision, first-principles lattice QCD calculation of the hadronic vacuum polarization (HVP) short-distance window contribution to the muon anomalous magnetic moment $a_\mu = (g-2)/2$. The result directly enters the current Standard Model prediction of $a_\mu$, a key benchmark for precision tests of fundamental particle physics.

HVP SD Comparison
Comparison of HVP short-distance window contributions to the muon $g-2$. The result of our calculation is labeled SL-24. This plot is taken from the 2025 Muon $g-2$ Theory Initiative White Paper.

presentations & posters

beyond the lab

CrossFit Open 23.2
CrossFit Open 23.2

Most days off involve a barbell, good company, or both.