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Title: Relations in the space of (2,0) heterotic string models
Author: Athanasopoulos, P.
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2016
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Understanding better the landscape of string models and eventually finding, if possible, a dynamical way to select among them is one of the most interesting, open problems in string theory. In this thesis, we investigate aspects of the heterotic landscape and discuss relations among large classes of vacua. The first part of the thesis is devoted to the equivalence between free fermionic models and orbifolds. Free fermionic models and symmetric heterotic toroidal orbifolds both constitute exact backgrounds that can be used effectively for phenomenological explorations within string theory. It is widely believed that for Z_2xZ_2 orbifolds the two descriptions should be equivalent, but a detailed dictionary between both formulations was lacking. A detailed account of how the input data of both descriptions can be related to each other can be found in this thesis. In particular, we show that the generalized GSO phases of the free fermionic model correspond to generalized torsion phases used in orbifold model building. We illustrate our translation methods by providing free fermionic realizations for all Z_2xZ_2 orbifold geometries in six dimensions. In the second half of the thesis, we turn our attention to a novel idea called spinor-vector duality. In its original form, spinor-vector duality was limited to Z_2 structures. Here, we use the language of simple currents to generalize this idea to theories with arbitrary internal RCFTs. We also elucidate the underlying spectral flow structure. Even though the spectral flow has been traditionally used to relate states within a single model, we offer a new way to look at it, allowing relations between different models. Contrary to the equivalence between free fermionic models and orbifolds, many of the models related by the spectral flow are not physically equivalent. Nevertheless, the The idea of grouping together models into families according to the spectral flow orbit is quite important: the spectra of the models, though not identical, are related and we can make statements about models in the entire family by examining one representative. The grouping also offers a conceptual handle, acting as an organization principle in a vast landscape of models.
Supervisor: Faraggi, A. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral