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Speakers: David Weir (Nottingham University), Lars Aalsma (University of Amsterdam), and Jorinde Van De Vis (Nikhef). Location: Amsterdam.

Event details of Theoretical Cosmology meeting
Date 7 June 2019
Time 13:30 -17:00


13:30 – 14:30 David Weir (Nottingham University) Vorticity, kinetic energy, and suppressed gravitational wave production in strong first order phase transitions

14:30 – 15:00 Coffee

15:00 – 16:00 Lars Aalsma (University of Amsterdam)De Sitter Space in the Unruh State

16:00 – 17:00 Jorinde Van De Vis (Nikhef) - An effective approach to electroweak baryogenesis


David Weir (Nottingham University) 

Vorticity, kinetic energy, and suppressed gravitational wave production in strong first order phase transitions 

In the Standard Model, electroweak symmetry breaking is a crossover. In many extensions, the phase transition can be of first order – even strongly so. The resulting phase transition can then be a substantial source of gravitational waves. For a phase transition at or around the electroweak scale, these gravitational waves may be detectable by future or planned missions, such as LISA. This can indirectly provide a probe of particle physics beyond the Standard Model, complementary to future colliders. In this talk I will discuss the physics that will make this possible and present some new simulation results for strong phase transitions, showing that vorticity is generated during the phase transition and substantial reheating can occur in front of the bubbles. This slows them down and, in certain cases, can suppress the generation of gravitational waves from the phase transition.

Lars Aalsma (University of Amsterdam)

De Sitter Space in the Unruh State

In this talk, I will discuss some recent work done in collaboration with Maulik Parikh and Jan Pieter van der Schaar in which we constructed a new quantum state for de Sitter space: the Unruh-de Sitter state. This state is the analogue of the Unruh state describing an evaporating black hole. I will show how to construct this state and calculate the stress tensor in an explicit two-dimensional example. After generalizing the computation to four dimensions I will analyze backreaction and show that de Sitter space exhibits a quantum instability in the Unruh state. Finally, I will comment on the possible implications of these results on (inflationary) cosmology.

Jorinde Van De Vis (Nikhef)

An effective approach to electroweak baryogenesis

The asymmetry between matter and antimatter is a one of the big outstanding questions of particle physics and cosmology. In this talk, I will argue that electroweak baryogenesis is an interesting mechanism to generate the baryon asymmetry. The new physics needed for electroweak baryogenesis come into play at a relatively low scale and can thus be tested in experiment.
In the first part of this talk I will explain whether electroweak baryogenesis can be studied in the model-independent framework of the Standard Model Effective Field Theory. In the second part I will make a comparison between the value of the asymmetry resulting from CP-violating interactions involving different Standard Model particles.


The meeting will take place at Nikhef, Science Park 105, 1098 XG Amsterdam, room H331. GoogleMaps>>

Local organiser

Jan Pieter van der Schaar


These meetings occur (roughly) every month and are hosted by universities across the Netherlands and sometimes Belgium, gathering the local cosmology community. Some of these talks might be of interest also for string and the Amsterdam GRAPPA groups, so we encourage you to subscribe to the THC mailing list:

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