As the detection of a stochastic gravitational wave background from the early universe becomes increasingly promising, signals from hypothetical first-order phase transitions are attracting growing interest. Predicting these signals often requires the solution of plasma dynamics at macroscopic scales, which, in turn, depends on the phenomena that characterize the phase transition at microscopic scales. Therefore, various assumptions on distinctive scales and their separation are usually employed to enable concrete evaluations. This workshop aims to bring together researchers from both the microscopic and macroscopic communities to collaboratively address theoretical shortcomings and refine current gravitational wave spectral templates across different regimes.

1. Microscopic scales – Quantitative uncertainties affect the fundamental phase transition parameters within minimal scenarios beyond the Standard Model, where a scalar field drives the symmetry-breaking mechanism.

2. Intermediate scales – Different approaches have been employed to describe the interactions between the scalar field and the plasma, including bubble wall dynamics and plasma viscosity. A key question is, e.g., whether the bubble wall runs away or reaches a terminal velocity.

3. Macroscopic scales – Several approximations are used to connect to large-scale phenomena during and after the phase transition, such as collisions between the bubbles, the development of turbulence, and the evolution of sound shells.

Confirmed speakers:

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Andrii Dashko, DESY

Wen-Yuan Ai, U. Vienna

Jani Dahl, U. Helsinki

Tae Hyun Jung, IBS

Ryusuke Jinno, U. Kobe

Lorenzo Giombi, U. Helsinki

Anna Kormu, U. Helsinki

Benoit Laurent, U. McGill

Mark Hindmarsh, U. Helsinki

Kari Rummukainen, U. Helsinki

Andrew J. Long, Rice U.
Tina Kahniashvili, U. Carnegie Mellon

Bogumila Swiezewska, U. Warsaw

 
Thomas Konstandin, DESY 

 
 
Marek Lewicki, U. Warsaw

 
 
Antonino S. Midiri, U. Geneva

Format: online participation is possible, but in-person attendance is limited. Talks are in person.

Registration: the deadline is on May 30, 2025. The call for abstracts is open until June 14, 2025.

This event is sponsored by the Department of Theoretical Physics at CERN as well as the CERN-Korea collaboration program.

Organizing committee:

Chiara Caprini (CERN & University of Geneva)

Hyun Min Lee (Chung-Ang University)

Seong Chan Park (Yonsei University)

Simona Procacci (University of Geneva)

Alberto Roper Pol (University of Geneva)

Philipp Schicho (University of Geneva)

Jorinde van de Vis (CERN)

NOTE: several participants have received phishing messages offering to book accommodation for the event. We do not send such messages as all participants need to make their own accommodation arrangements.