Advancing gravitational wave predictions from cosmological first-order phase transitions

Session

Intermediate scales

26 Aug 2025, 10:30

4/3-006 - TH Conference Room (CERN)

Conveners

Intermediate scales: Morning session

• Alberto Roper Pol

Intermediate scales: Afternoon session

• Seong Chan Park

Intermediate scales: Short talks

• Jorinde van de Vis (CERN)

Intermediate scales: Morning session

• Chiara Caprini (CERN)

Intermediate scales: Morning session

• Chiara Caprini (CERN)

Intermediate scales: Panel Discussion

• Jorinde van de Vis (CERN)

Description

To join the discussion poll, use the following link and code.

intermediate scales:
https://www.menti.com/al7v358nsur8
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Presentation materials

discussion_intermediate_scales_results.pdf

2. An effective-theory perspective on bubble nucleation and growth

Mikko Sakari Laine (Universitaet Bern (CH))

26/08/2025, 10:30

Microscopic scales

Certain aspects of phase transition dynamics, at least the initial nucleations and subsequent growth, can be described within the framework of fluctuating hydrodynamics, extended by a scalar order parameter. A strength of this formulation is that the contributions of small and large momenta can be factorized. We describe the ideas and limitations behind this approach, and how it can be used...

23. Microscopic particle processes during bubble expansion and new high-frequency gravitational waves

Wen-Yuan Ai

26/08/2025, 11:15

In certain scenarios, bubble walls may reach a velocity with a very large Lorentz boost factor or run away. For such ultrarelativistic bubble walls, a new energy scale $\gamma_w T$ emerges, allowing for the production of heavy particles. I will discuss the dynamics of ultrarelativistic bubble walls and the associated heavy dark matter and gravitational wave production.

24. Bubble-wall velocity with loop corrections

Andrii Dashko (DESY Theory)

26/08/2025, 13:30

In this work, the dynamics of the nucleating scalar field is investigated during
the first-order phase transitions by incorporating one-loop corrections of classical fluctuations.
We contrast our results with traditional methods based on the derivative expansion; show that the latent heat can differ from the effective-potential result; and discuss general hydrodynamic corrections....

22. Bounds on bubble wall velocity and application to first-order QCD phase transition

Benoit Laurent (CEA / DAM Ile de France (FR))

26/08/2025, 14:15

In this talk, I will take advantage of recent progress on wall speed determination to provide simple estimates that constrain the wall velocity between two opposite limits: local thermal equilibrium and ballistic. The description of the wall velocity in these limits is significantly simplified compared to conventional methods, which allows for the derivation of analytic formulas valid for slow...

12. Examples of GW from FOPT and WallGo

Liliana Velasco-Sevilla (Sogang University, South Korea)

26/08/2025, 15:30

Examples of GW from FOPT in BSM models and WallGo: I present three examples of BSM producing GW: one from SO(10) from the breaking chain $SU(3)_C\times SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ (2506.07182), another from a first-order phase transition of the inflaton coupled to a dark sector (2412.17278) and the third one from reheating through particle production. As we know, uncertainties in...

6. Bubble wall velocity from hydrodynamics

Mateusz Zych (University of Warsaw)

26/08/2025, 15:35

Terminal velocity of bubble walls in cosmological first-order phase transitions is a key parameter affecting both the primordial gravitational wave signal and baryon asymmetry production in electroweak baryogenesis. In this talk, I present recent results showing that, under local thermal equilibrium, pure hydrodynamic backreaction can lead to steady-state expansion, as confirmed by numerical...

8. Bubble wall dynamics and the electroweak phase transition

Carlo Branchina (Università della Calabria)

27/08/2025, 09:15

The dynamics of of the electroweak phase transition has profound implications for cosmology and particle physics, and is governed by the density perturbations generated by the expanding bubble. A precise determination of this dynamics, and in particular of the bubble wall velocity, is crucial to assess the experimental signatures of the transition. In this talk, I will report on recent...

26. Strong cosmological phase transitions and their gravitational wave signals

Marek Lewicki (University of Warsaw)

27/08/2025, 10:30

We are currently witnessing the dawn of a new era in astrophysics and cosmology, started by the LIGO/Virgo observations of Gravitational Waves (GWs). Recently, also the detection of a stochastic background of GWs at very low frequencies was announced by the Pulsar Timing Array collaborations. In this talk, I will discuss terminal velocities reached by expanding bubble walls and the GW signals...

9. From symmetries to gravitational waves: a self-consistent calculation

Csaba Balazs (Monash University)

27/08/2025, 11:15

Intermediate scales

Predicting the gravitational wave spectrum from symmetry breaking in the early universe during first-order phase transitions is key to understanding these symmetries. In this talk I present our recent advancements in developing a self-consistent framework for predicting such gravitational wave spectra. Our approach enhances existing calculations by providing a more comprehensive treatment of...