Philipp Schicho

Research fellow

Département de Physique Théorique
Université de Genève

Biography

Hi everyone! 👋
As a research fellow in theoretical physics, I investigate quantum theories under extreme conditions, probing very dense and hot regimes such as in compact star astrophysics and early universe cosmology. I also automate multi-loop calculations at finite temperature and density.

Since autumn 2024, I have been the principal investigator of PRECLISA: Gravitational waves from cosmological phase transitions: Precision cosmology in the light of LISA (SNSF project no. 215997). Through this grant, funded by the Swiss National Science Foundation, I lead the Thermal field theory, Particles, and Cosmic phases (TPC) group.

Interests

Early universe cosmology
Cosmological phase transitions
Multi-loop computations

Education

PhD in high-energy physics, 2020

University of Bern
MSc in Physics, 2016

ETH Zürich

Experience

SNSF Ambizione fellow

Départment de Physique Théorique, Université de Genève

Sep 2024 – Present Genève

Postdoctoral researcher

Institute for Theoretical Physics, Goethe University

Sep 2022 – Aug 2024 Frankfurt am Main

Postdoctoral researcher

University of Helsinki, Helsinki Institute of Physics

May 2020 – Aug 2022 Helsinki

Doctor of Philosophy, PhD Physics

University of Bern

Feb 2017 – Apr 2020 Bern

Thermal field theory and particle cosmology.
Advisor: Mikko Laine
Multi-loop investigations of strong interactions at high temperatures.

Technical student

CERN, Accelerator and Beam Transfer, Beam Transfer Physics

Oct 2016 – Jan 2017 Genève

Theoretical optimisation of slow extraction.
Advisors: Matthew A. Fraser, Malika Meddahi

Summer student

CERN, Accelerator and Beam Transfer, Beam Transfer Physics

Jun 2015 – Aug 2015 Genève

Optimising simulation times of SPS slow extraction using MAD-X.

Master of science, Physics

Eidgenössische Technische Hochschule (ETH)

Sep 2014 – Nov 2016 Zürich

GPA: 5.5/6.0
Theoretical high energy physics, lattice QCD, applied mathematics.
Advisor: Philippe de Forcrand
Thesis: Inhomogeneous condensation in quark-based QCD effective models via wavelet pseudoparticles.

Selected publications

J. Löfgren, M. J. Ramsey-Musolf, P. Schicho, and T. V. I. Tenkanen, Nucleation at Finite Temperature: A Gauge-Invariant Perturbative Framework, Phys. Rev. Lett. 130, 251801 (2023), [2112.05472].
A. Ekstedt, P. Schicho, and T. V. I. Tenkanen, DRalgo: A package for effective field theory approach for thermal phase transitions, Comput. Phys. Commun. 288, 108725 (2023), [2205.08815].
A. Ekstedt, P. Schicho, and T. V. I. Tenkanen, Cosmological phase transitions at three loops: The final verdict on perturbation theory, Phys. Rev. D 110, 096006 (2024), [2405.18349].
D. Croon, O. Gould, P. Schicho, T. V. I. Tenkanen, and G. White, Theoretical uncertainties for cosmological first-order phase transitions, JHEP 2021, 55 (2021), [2009.10080].

See all publications

Thermal field theory, Particles, and Cosmic phases group

My research group investigates quantum theories under extreme conditions, exploring the dense and hot regimes that appear in compact star astrophysics and the early universe, while also seeking signs of new physics at the electroweak scale. Studying theories at finite temperature and density requires combining perturbative and non-perturbative methods to unravel their phase structure. Developing and applying this interplay of theoretical tools is at the heart of the Thermal field theory, Particles, and Cosmic phases group.

Group members

PhD students: Fabio Bernardo

Master students: Salma Kämpf, Romain Guillermo Reinle

Former students: Rebecca Baumann, Sami Vihko

Visitors: Francesco Rescigno

Research projects

Precision thermodynamics for cosmological phase transitions

Understanding the connection between the matter content of the universe and its thermal history is a major challenge in cosmology. The detection of gravitational waves (GW) from binary black hole mergers at LIGO has invigorated efforts to scope the universe in a broad temperature range and answer the question: is there new physics at the electroweak scale? The electroweak phase transition (EWPT) in beyond the Standard Model (BSM) theories could give rise to strong first-order phase transitions (cf. fig. left) relevant to explain Baryogenesis and in turn the Baryon asymmetry of the universe. Such transitions can occur via complex multi-step transitions.

DRalgo: automated 3d EFT framework for thermal field theories

DRalgo is an algorithmic implementation that constructs an effective high-temperature theory for generic models.

How fast does the WallGo? A package for computing wall velocities in first-order phase transitions

WallGo is an open source code for the computation of the bubble wall velocity and bubble wall width in first-order cosmological phase transitions. The main WallGo Python package determines the wall velocity and width by solving the scalar field(s) equation of motion, the Boltzmann equations and energy-momentum conservation for the fluid velocity and temperature.

Cold dense matter and QCD pressure

Determining the physical phase of matter inside neutron stars has been a long standing challenge. The central object to inspect is the equation of state of neutron stars which by including astrophysical observations can be constrained tightly.

Outreach & Teaching

Lectures

Theoretische Physik 1: Mathematische Ergänzungen (Skript)

Exercises at Phase transitions in the early universe at the Theoretical Aspects of Astroparticle Physics, Cosmology and Gravitation school at the Galileo Galilei Institute for Theoretical Physics

Recent & Upcoming Talks

Strong electroweak phase transition and simplified dark matter models

Beyond the Standard Model physics is required to explain both dark matter and the baryon asymmetry of the universe, the latter possibly generated during a strong first-order electroweak phase transition. While many proposed models tackle these problems independently, it is interesting to inquire whether the same model can explain both. We focus on a dark matter model featuring an inert Majorana fermion that is coupled to Standard Model leptons via a scalar mediator. The latter interacts directly with the Higgs boson. We link state-of-the-art perturbative assessments of the phase transition thermodynamics with the extraction of the dark matter energy density. We discern regions of the model parameter space that reproduce the observed dark matter energy density and allow for a first-order phase transition, while evading the most stringent collider constraints.