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Accurate relic densities with neutralino, chargino and sfermion coannihilations in mSUGRA
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
SISSA, via Beirut 4, I-34014 Trieste.
Department of Physics, Case Western Reserve University, 10900 Euclid Ave, Cleveland.
2003 (English)In: Journal of Cosmology and Astroparticle Physics, Vol. 04, 001-029 p.Article in journal (Refereed) Published
Abstract [en]

Neutralinos arise as natural dark matter candidates in many supersymmetric extensions of the Standard Model. We present a novel calculation of the neutralino relic abundance in which we include all so-called coannihilation processes between neutralinos, charginos and sfermions, and, at the same time, we apply the state of the art technique to trace the freeze-out of a species in the early Universe. As a first application, we discuss here results valid in the mSUGRA framework; we describe general trends as well as performing a detailed study of the neutralino relic densities in the mSUGRA parameter space. The emerging picture is fair agreement with previous analyses in the same framework, however we have the power to discuss it in much more detail than previously done. For example, we find that the cosmological bound on the neutralino mass is pushed up to ~565 GeV in the stau coannihilation region and to ~1500 GeV in the chargino coannihilation region.

Place, publisher, year, edition, pages
Institute of Physics Pub , 2003. Vol. 04, 001-029 p.
Keyword [en]
dark matter, string theory and cosmology
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:su:diva-23218OAI: oai:DiVA.org:su-23218DiVA: diva2:190743
Note
Part of urn:nbn:se:su:diva-192Available from: 2004-05-19 Created: 2004-05-19 Last updated: 2010-01-04Bibliographically approved
In thesis
1. Supersymmetric Dark Matter: aspects of sfermion coannihilations
Open this publication in new window or tab >>Supersymmetric Dark Matter: aspects of sfermion coannihilations
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There is very strong evidence that ordinary matter in the Universe is outweighed by almost ten times as much so-called dark matter. Dark matter does neither emit nor absorb light and we do not know what it is. One of the theoretically favoured candidates is a so-called neutralino from the supersymmetric extension of the Standard Model of particle physics.

A theoretical calculation of the expected cosmic neutralino density must include the so-called coannihilations. Coannihilations are particle processes in the early Universe with any two supersymmetric particles in the initial state and any two Standard Model particles in the final state. In this thesis we discuss the importance of these processes for the calculation of the relic density. We will go through some details in the calculation of coannihilations with one or two so-called sfermions in the initial state. This includes a discussion of Feynman diagrams with clashing arrows, a calculation of colour factors and a discussion of ghosts in non-Abelian field theory.

Supersymmetric models contain a large number of free parameters on which the masses and couplings depend. The requirement, that the predicted density of cosmic neutralinos must agree with the density observed for the unknown dark matter, will constrain the parameters. Other constraints come from experiments which are not related to cosmology. For instance, the supersymmetric loop contribution to the rare b -> decay should agree with the measured branching fraction. The principles of the calculation of the rare decay are discussed in this thesis. Also on-going and planned searches for cosmic neutralinos can constrain the parameters. In one of the accompanying papers in the thesis we compare the detection prospects for several current and future searches for neutralino dark matter.

Place, publisher, year, edition, pages
Stockholm: Fysikum, 2004. 157 p.
Keyword
Supersymmetry, Dark Matter
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-192 (URN)91-7265-909-2 (ISBN)
Public defence
2004-06-11, sal FB53, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 14:00
Opponent
Supervisors
Available from: 2004-05-19 Created: 2004-05-19Bibliographically approved

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