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Expansion history and f(R) modified gravity
Stockholm University, Faculty of Science, Department of Physics. (cops)
2007 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, no 12, 005- p.Article in journal (Refereed) Published
Abstract [en]

We attempt to fit cosmological data using f(R) modified Lagrangians containing inverse powers of the Ricci scalar varied with respect to the metric. While we can fit the supernova data well, we confirm the behaviour at medium to high redshifts reported elsewhere and argue that the easiest way to show that this class of models are inconsistent with the data is by considering the thickness of the last scattering surface. For the best fit parameters to the supernova data, the simplest 1/R model gives rise to a last scattering surface of thickness Δz~530, inconsistent with observations.

Place, publisher, year, edition, pages
2007. no 12, 005- p.
National Category
Physical Sciences
URN: urn:nbn:se:su:diva-12508DOI: 10.1088/1475-7516/2007/12/005ISI: 000251993400013OAI: diva2:179028
Available from: 2008-01-15 Created: 2008-01-15 Last updated: 2011-05-03Bibliographically approved
In thesis
1. Phenomenological Studies in Cosmoparticle Physics: Expansion Histories in non-Einstein Gravity and Dark Matter at the Large Hadron Collider
Open this publication in new window or tab >>Phenomenological Studies in Cosmoparticle Physics: Expansion Histories in non-Einstein Gravity and Dark Matter at the Large Hadron Collider
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

As the Big Bang model has become established, the fields of cosmology and particle physics have become intertwined. A range of observations forces us to consider the phenomena of dark matter and dark energy. This interpretation is based on our understanding of gravity, while the standard model of particle physics describes the other fundamental forces in nature and fails to explain the dark components. This thesis includes two different types of studies where hypotheses of physics beyond the standard models of particle physics and cosmology are faced with what observations and experiments can tell us.

The first one deals with the possibility that our theory of gravity is what has to be modified at large distances to explain the dark energy, which then need not be a contribution to the energy content at all. The expansion histories in two such frameworks are tested with data from type Ia supernovae and measurements of the baryon acoustic peak in the galaxy distribution as well as in the cosmic microwave background.

The second type of study concerns the possibility of establishing the particle nature of dark matter through interactions other than gravitational. While there are ways of doing this using astrophysical observations, the uncertainties due to astrophysics and the unknown distribution of the dark matter are large. High energy particle colliders provide a way of imitating the conditions of the early universe in the laboratory, where we can hope to produce yet unknown heavy particle states and in a more controlled environment determine their properties. We study the prospects for discovering two types of weakly interacting dark matter candidates at the CERN Large Hadron Collider.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholms University, 2011. 48 p.
National Category
Natural Sciences
Research subject
Theoretical Physics
urn:nbn:se:su:diva-56952 (URN)978-91-7447-302-5 (ISBN)
Public defence
2011-06-01, sal FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript. Available from: 2011-05-10 Created: 2011-05-02 Last updated: 2011-05-03Bibliographically approved

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Rydbeck, Sara
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