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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Leuven Spring 2017

07/04/2017 @ 12:00 - 18:00

KU Leuven, April 7, 2017

Location: Arenberg Castle, Kardinaal Mercierlaan 94, 3001 Leuven (Heverlee)

For organisational reasons (such as pre-meeting lunch and bus), please sign up for the meeting by clicking “I am coming” here:

13.00-14.00 Talk by Kate Eckerle (Columbia University, USA)
Title: Axions of Evil – a novel type of alignment that renders complex theories tractable
Abstract: I will discuss a lattice reduction procedure developed recently for locating vacua in random axion landscapes involving more instanton contributions to the effective potential than number independent axion fields, N. The lattice framework is worthy of discussion in and of itself because it serves as more than simply a tool for identifying vacua. It casts the large N limit as of a novel type of alignment. Both the exact and the approximate discrete shift symmetries of a given (large dimensional) random axion model are displayed in a natural fashion.
By rendering even complex theories analytically tractable the answers to many questions of cosmological interest can be obtained. These models, it turns out, accommodate a diverse range of inflationary observables. We find, somewhat remarkably, that many macroscopic features of our own universe can be reproduced without tuned parameters.
(45min Talk + 15min discussion)

14.00-15.00 Talk by Joseph Conlon (University of Oxford, UK)
Title: String theory and cosmology – ships that pass in the night?

Abstract: Where is string theory an unavoidable part of cosmology? I claim there are two areas where knowledge of Planck scale physics is essential for observational effects accessible in modern cosmology.
The first area is the question of observable tensor modes in the CMB. These are related to the presence of transPlanckian field excursions during inflation. Although no decisive line of argument has yet arisen, many independent strands of evidence suggest that transPlanckian field excursions should be censored in a quantum theory of gravity.
The second area is the presence of relic dark radiation. The importance of heavy particles at reheating scales inversely with their couplings, and measurements of the abundance of dark radiation highly constrain the behaviour of Planck-coupled particles in the early universe at the time of reheating.
(45min Talk + 15min discussion)

15.00-15.30: Coffee Break

15.30-16.45 Talk by Savdeep Sethi (KICP Chicago, USA)
Title: Supersymmetry Breaking by Fluxes
Abstract: I will overview both no-go constraints on building landscapes in string theory, and some of the proposed landscape constructions that purport to evade these constraints. I will propose an explanation for the apparent tension between the no-go results and the proposed constructions by revisiting supersymmetry breaking by fluxes. The talk essentially summarizes my current view on landscape constructions.
(45min Talk + 30min discussion)

16.45-18.30: Reception with beer and various snacks


12:00 - 18:00
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KU Leuven
Kardinaal Mercierlaan 94
Leuven, 3001 Belgium
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