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dc.contributor.advisorKenway, Richard
dc.contributor.advisorDel Debbio, Luigi
dc.contributor.authorLambrou, Eliana
dc.date.accessioned2017-02-08T16:04:16Z
dc.date.available2017-02-08T16:04:16Z
dc.date.issued2016-06-29
dc.identifier.urihttp://hdl.handle.net/1842/19579
dc.description.abstractThe idea that we live in a higher-dimensional space was first introduced almost 100 years ago. In the past two decades many extra-dimensional models have been proposed in order to solve fundamental problems of nature such as the hierarchy problem. Most of them need exploration via non-perturbative approaches and Lattice Gauge Theory provides a tool for doing this. In this thesis, we make attempts to find a non-perturbative way to localize gauge fields that arise from five-dimensional SU(2) gauge theories on 3-branes. In 1984, it was proposed that the phase diagram of anisotropic extra-dimensional lattice gauge theories inherits a new phase, called the "layered" phase, where the gauge fields behave as four-dimensional ones. This was shown for the abelian case, but the existence of this new phase for the simplest non-abelian group, SU(2), was still in doubt. We investigated this system in large volumes using Monte Carlo simulations and we could not find a second order phase transition from a five-dimensional to a continuous four-dimensional theory when all directions were kept large. This made the model unattractive for further exploration as nothing suggests that a non-trivial fixed point could exist. The above investigation was done in a flat background metric. We extended the previous work by putting our theory into a slice of AdS5 space, usually called the warped background. The motivation for this is that our SU(2) theory looks like the gauge-sector of the Randall-Sundrum model, which does not have a concrete solution to the problem of localization of the gauge fields on a 3-brane. We carried out our investigation using the Mean-Field Approach and we present novel results for the phase diagram and measurements of important observables. In our implementation we have a finite extent of the extra dimension and one layer (or 3-brane) on each extra-dimensional coordinate. At weak coupling, we observed that each layer decouples one at a time in the transition to the fully layered phase of the system, forming a mixed phase, whereas there is a strong and sharp transition between the fully layered and the strong-coupling phase. Within the mixed phase, close to the transition into the layered phase, we found evidence that the system is four-dimensional acquiring a Yukawa mass and resembling a Higgs-like phase. The mixed phase grows as the curvature increases suggesting that for an infinite extra dimension the entire weak-coupling phase is mixed.en
dc.contributor.sponsorScience and Technology Facilities Council (STFC)en
dc.language.isoenen
dc.publisherThe University of Edinburghen
dc.relation.hasversionL. Del Debbio, R. D. Kenway, E. Lambrou, and E. Rinaldi,"The transition to a layered phase in the anisotropic five-dimensional SU(2) Yang-Mills theory", Phys.Lett., vol. B724, no. 1-3, pp. 133-137, 2013.en
dc.relation.hasversionL. Del Debbio, R. D. Kenway, E. Lambrou, and E. Rinaldi,"Searching for a continuum 4D field theory arising from a 5D non-abelian gauge theory", PoS, vol. LATTICE2013, p. 107, 2014.en
dc.relation.hasversionR. D. Kenway, E. Lambrou, "Five-dimensional gauge theories in a warped background", PoS, vol. LATTICE2015, p. 232, 2016.en
dc.subjectLattice Gauge Theoryen
dc.subjectAdS5 spaceen
dc.subjectMean-Field Approachen
dc.subjectYukawa massen
dc.subjectHiggs-like phaseen
dc.subjectweak-coupling phaseen
dc.titlePhase structure of five-dimensional anisotropic lattice gauge theoriesen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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