Dissertation / PhD Thesis

PUBDB-2026-01897

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Advancing the Perturbative Description of the Electroweak Phase Transition: Loops, Bubbles and Gravitational Waves

Dashko, A. (Corresponding author)DESY* ; Weiglein, G. (Thesis advisor)DESY* ; Servant, G. (Thesis advisor)DESY*

2026

This record in other databases:  

Please use a persistent id in citations: urn:nbn:de:gbv:18-ediss-138223  doi:10.3204/PUBDB-2026-01897

Abstract: The nature of the electroweak phase transition (EWPT) in the early Universe plays acentral role in connecting particle physics with cosmology. In the Standard Model (SM),the EWPT is a smooth crossover, forbidding electroweak baryogenesis and yielding noobservable gravitational-wave (GW) signal. In contrast, many SM extensions allow fora strong first-order EWPT, opening the possibility of explaining the baryon asymmetryand generating stochastic GW backgrounds.This thesis investigates the EWPT in Beyond the SM (BSM) scenarios, focusing on thechallenge of reliably determining thermodynamic observables by reducing the remain-ing theoretical uncertainties. To address this, different perturbative approaches are con-trasted, in particular conventional four-dimensional (4D) finite-temperature methodsand a dimensionally reduced three-dimensional (3D) effective field theory (EFT) frame-work exploiting the separation of thermal scales.In the complex singlet extension of the SM (cxSM) featuring a strong first-order EWPT,we employ residual gauge and scale dependence as a diagnostic tool to quantify theoret-ical uncertainties, showing that the 3D EFT framework yields more robust predictionswithin the regime of validity of the EFT expansion.In the 3D EFT framework, we derive the renormalization group evolution of the effec-tive couplings for the 3D EFT of the Standard Model Effective Field Theory (SMEFT),systematically incorporating higher-dimensional operators. This enables consistent re-summation of logarithmic corrections and paves the way for more precise perturbativecalculations and lattice simulations of the EWPT.Furthermore, we develop a systematic framework to incorporate one-loop correctionsinto the nucleating bubble wall equation of motion, thereby enhancing the accuracy andreliability of bubble wall velocity calculations.Overall, this thesis advances the precision program for EWPT studies by systematicallyaddressing theoretical uncertainties, improving perturbative frameworks, and refiningGW predictions. These developments are crucial for interpreting future observations,particularly from experiments such as LISA, and for using GWs as a probe of new physicsin the early Universe.

Note: Dissertation, Universität Hamburg, 2026

---

Contributing Institute(s):

1. Theorie-Gruppe (T)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF4-611) (POF4-611)
2. DFG project G:(GEPRIS)390833306 - EXC 2121: Das Quantisierte Universum II (390833306) (390833306)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2026

---

Database coverage:
;

---