Theoretical Cosmology meetings

To actively encourage the field of theoretical cosmology and to set an informal stage for the exchange of ideas, the Dutch theoretical cosmology community organizes Friday afternoon meetings approximately 6 times a year — usually on the first Friday of the month. The meetings typically start in the afternoon with a main speaker, followed by a short break to continue with another seminar or journal club discussion on some topic of current interest. We end the afternoon with drinks. The supporting institutes in Leiden, Amsterdam, Groningen, Utrecht where recently joined by the strings and cosmology group in Leuven and take turns in hosting the event.

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Amsterdam Spring 2019

07/06/2019 @ 13:30 - 17:00

Amsterdam, June 7th. The meeting will take place at Nikhef, Science Park 105, 1098 XG Amsterdam, room H331.


13:30 – 14:30: Talk by David Weir (Nottingham University)

Title: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.

14:30 – 15:00: Coffee

15:00 – 16:00: Talk by Lars Aalsma(UvA)

Title: 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.

16:00 – 17:00: Talk by Jorinde Van De Vis (Nikhef)

Title: 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.



13:30 - 17:00
Event Category:


Jan Pieter van der Schaar


Science Park 105
Amsterdam, 1098 XG
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+31 (0)20 592 2000