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Non-perturbative aspects of gauge theories from gauge-gravity dualities / JOHN ROUGHLEY

Swansea University Author: JOHN ROUGHLEY

DOI (Published version): 10.23889/SUthesis.58266

Abstract

In this Ph.D. Thesis we consider two speci˝c supergravities which are well-established within the literature on holography, and which are known to provide the low-energy e˙ective description of either superstring theory or M-theory: the six-dimensional half-maximal theory of Romans, and the maximal...

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Published: Swansea 2021
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Piai, Maurizio ; Lucini, Biagio
URI: https://cronfa.swan.ac.uk/Record/cronfa58266
first_indexed 2021-10-07T16:58:15Z
last_indexed 2021-10-08T03:23:25Z
id cronfa58266
recordtype RisThesis
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spelling 2021-10-07T18:11:24.6283172 v2 58266 2021-10-07 Non-perturbative aspects of gauge theories from gauge-gravity dualities c5ee7cb20c80e8180af79038e7659ab7 JOHN ROUGHLEY JOHN ROUGHLEY true false 2021-10-07 In this Ph.D. Thesis we consider two speci˝c supergravities which are well-established within the literature on holography, and which are known to provide the low-energy e˙ective description of either superstring theory or M-theory: the six-dimensional half-maximal theory of Romans, and the maximal supergravity in seven dimensions.We implement their dimensional reduction by compactifying on an S1 and T 2, respectively, to obtain a ˝ve-dimensional sigma-model coupled to grav-ity. Spectra of bosonic excitations are computed numerically by considering ˝eld ˛uctuations on background geometries which holographically realise con-˝nement. We furthermore propose a diagnostic tool to detect mixing e˙ects between scalar resonances and the pseudo-NambuGoldstone boson associated with spontaneous breaking of conformal invariance: the dilaton. This test con-sists of neglecting a certain component of the spin-0 ˛uctuation variables, ef-fectively disregarding their back-reaction on the underlying geometry; where discrepancies arise compared to the complete calculation we infer dilaton mix-ing. For both theories this analysis evinces a parametrically light dilaton.For each supergravity we uncover a tachyonic instability within their param-eter space; motivated by these pathological ˝ndings we proceed to conduct an investigation into their respective phase structures, reasoning that there must necessarily exist some mechanism by which these instabilities are rendered phys-ically inaccessible. We compile a comprehensive catalogue of geometrically dis-tinct backgrounds admissible within each theory, and derive general expressionsfor their holographically renormalised free energy F. Another numerical rou-tine is employed to systematically extract data for some special deformationparameters, and F is plotted in units of an appropriate universal scale.Our analysis proves fruitful: each theory exhibits clear evidence of a ˝rst-order phase transition which induces the spontaneous decompacti˝cation of the shrinking circular dimension before the instability manifests, favouring instead a class of singular solutions. The aforementioned dilaton resonance appears only along a metastable portion of the branch of con˝ning backgrounds. E-Thesis Swansea Gauge/gravity duality; Holography; Supergravity 7 10 2021 2021-10-07 10.23889/SUthesis.58266 ORCiD identifier https://orcid.org/0000-0001-7299-6781 COLLEGE NANME COLLEGE CODE Swansea University Piai, Maurizio ; Lucini, Biagio Doctoral Ph.D Science and Technology Facilities Council (STFC) - Grant number ST/R505158/1 2021-10-07T18:11:24.6283172 2021-10-07T17:50:15.0101556 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics JOHN ROUGHLEY 1 58266__21113__67df21f4c00c43d5a059cd5ad89d81b0.pdf Roughley_John_PhD_Thesis_Final.pdf 2021-10-07T18:02:42.7382905 Output 6823750 application/pdf E-Thesis – open access true Copyright: The author, John Roughley, 2021. true eng
title Non-perturbative aspects of gauge theories from gauge-gravity dualities
spellingShingle Non-perturbative aspects of gauge theories from gauge-gravity dualities
JOHN ROUGHLEY
title_short Non-perturbative aspects of gauge theories from gauge-gravity dualities
title_full Non-perturbative aspects of gauge theories from gauge-gravity dualities
title_fullStr Non-perturbative aspects of gauge theories from gauge-gravity dualities
title_full_unstemmed Non-perturbative aspects of gauge theories from gauge-gravity dualities
title_sort Non-perturbative aspects of gauge theories from gauge-gravity dualities
author_id_str_mv c5ee7cb20c80e8180af79038e7659ab7
author_id_fullname_str_mv c5ee7cb20c80e8180af79038e7659ab7_***_JOHN ROUGHLEY
author JOHN ROUGHLEY
author2 JOHN ROUGHLEY
format E-Thesis
publishDate 2021
institution Swansea University
doi_str_mv 10.23889/SUthesis.58266
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 1
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description In this Ph.D. Thesis we consider two speci˝c supergravities which are well-established within the literature on holography, and which are known to provide the low-energy e˙ective description of either superstring theory or M-theory: the six-dimensional half-maximal theory of Romans, and the maximal supergravity in seven dimensions.We implement their dimensional reduction by compactifying on an S1 and T 2, respectively, to obtain a ˝ve-dimensional sigma-model coupled to grav-ity. Spectra of bosonic excitations are computed numerically by considering ˝eld ˛uctuations on background geometries which holographically realise con-˝nement. We furthermore propose a diagnostic tool to detect mixing e˙ects between scalar resonances and the pseudo-NambuGoldstone boson associated with spontaneous breaking of conformal invariance: the dilaton. This test con-sists of neglecting a certain component of the spin-0 ˛uctuation variables, ef-fectively disregarding their back-reaction on the underlying geometry; where discrepancies arise compared to the complete calculation we infer dilaton mix-ing. For both theories this analysis evinces a parametrically light dilaton.For each supergravity we uncover a tachyonic instability within their param-eter space; motivated by these pathological ˝ndings we proceed to conduct an investigation into their respective phase structures, reasoning that there must necessarily exist some mechanism by which these instabilities are rendered phys-ically inaccessible. We compile a comprehensive catalogue of geometrically dis-tinct backgrounds admissible within each theory, and derive general expressionsfor their holographically renormalised free energy F. Another numerical rou-tine is employed to systematically extract data for some special deformationparameters, and F is plotted in units of an appropriate universal scale.Our analysis proves fruitful: each theory exhibits clear evidence of a ˝rst-order phase transition which induces the spontaneous decompacti˝cation of the shrinking circular dimension before the instability manifests, favouring instead a class of singular solutions. The aforementioned dilaton resonance appears only along a metastable portion of the branch of con˝ning backgrounds.
published_date 2021-10-07T12:38:03Z
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