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Lorentz violatining brane-world models and their cosmological relevance

Final Activity Report Summary - LoBED (Lorentz Violatining Brane-World Models and their Cosmological Relevance)

Within the general context of high energy physics, this research work focussed on techniques and ideas based on the existence of ‘extra’ dimensions of space, beyond the usual three dimensions which we observe in everyday life. Two main motivations for this idea exist in particle physics and both of them were investigated within this project:

1. the use of extra dimensions to build models beyond the standard model of particle physics
2. the concept of holography, which used curved space-times extra dimensions to describe the physics of strongly coupled quantum field theories.

In the context of brane-world models, we studied the existence and lifetime of metastable, i.e. unstable but long-lived, vacua and examined how these could be used to construct models of supersymmetry breaking. In order to exploit the second motivation, we utilised the best known and understood holographic setups. We developed a class of phenomenological holographic models that captured the salient features of real-world quantum chromo-dynamics (QCD), e.g. running of the coupling and colour confinement. Furthermore, we showed that the thermodynamics of these models were also very similar to those of finite temperature QCD. This could in principle lead to an accurate quantitative description of the hydrodynamics of the quark-gluon plasma phase that is created in heavy-ion collision experiments. Such experiments were under way at the relativistic heavy ion collider (RHIC), as well as planned at the large hadron collider (LHC).