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Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD / EDWARD BENNETT

Swansea University Author: EDWARD BENNETT

DOI (Published version): 10.23889/SUthesis.38186

Abstract

In this thesis we investigate numerically SU(2) theories with Dirac—or Majorana—fermions in the adjoint representation. Majorana fermions have historically proven difficult to treat numerically; here, a change of basis is introduced that allows two Majorana fermions to be expressed in terms of one D...

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Published: 2013
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa38186
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spelling 2020-09-01T15:46:24.3636725 v2 38186 2018-01-19 Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD 427a653163238d69c8cf2c778bd59b07 EDWARD BENNETT EDWARD BENNETT true true 2018-01-19 In this thesis we investigate numerically SU(2) theories with Dirac—or Majorana—fermions in the adjoint representation. Majorana fermions have historically proven difficult to treat numerically; here, a change of basis is introduced that allows two Majorana fermions to be expressed in terms of one Dirac fermion. This also provides greater insight into the analysis of the properties of theories with Dirac fermions. Attention is focused on the SU(2) theory with a single Dirac flavour (or equivalently two Majorana flavours). Its lattice phase diagram, spectrum, and the anomalous dimension of the chiral condensate are investigated. We observe a long region of constant mass ratios and an anomalous dimension 0.9 ≲ γ∗ ≲ 0.95. The behaviour of the pion mass and the presence of a light scalar in particular point to behaviour that is not traditionally confining; instead the theory appears to lie in or near the conformal window. The topological susceptibility and instanton size distribution are also investigated, for the one-Dirac-flavour theory and additionally the pure-gauge and two-Dirac-flavour (Minimal Walking Technicolor) theories. The properties are found to not depend on number of flavours, indicating a quenching of the fermions in the topology, also consistent with (near-)conformal behaviour (as has previously been reported in studies of other observables for Minimal Walking Technicolor). The code used is described, and a high-performance computing benchmark developed from it is detailed. While the benchmark was originally developed to investigate the performance of different supercomputer architectures for the class of problems we are interested in. Due to the nature of the code on which it is based, it has an unusual flexibility in the demands it may place on machine’s performance characteristics, which may allow it to be applicable to problems outside of lattice physics. The benchmark is used to characterise a number of machines’ relative performance. E-Thesis Lattice gauge theory, beyond the standard model, walking technicolor, near-conformal theory, SU(2), topology, high-performance computing, benchmarking. 31 12 2013 2013-12-31 10.23889/SUthesis.38186 B2.License files for BSMBench. Copyright 2012, all rights reserved. See the re-use conditions for BSMBench, Thesis Appendix B. (p.129). COLLEGE NANME COLLEGE CODE Swansea University Doctoral Ph.D STFC ST/F00706X/1 2020-09-01T15:46:24.3636725 2018-01-19T14:59:54.7520918 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics EDWARD BENNETT 1 0038186-19012018150450.pdf Bennett_Edward_J_thesis-final.pdf 2018-01-19T15:04:50.4230000 Output 18397218 application/pdf E-Thesis – open access true 2018-01-19T00:00:00.0000000 true
title Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD
spellingShingle Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD
EDWARD BENNETT
title_short Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD
title_full Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD
title_fullStr Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD
title_full_unstemmed Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD
title_sort Physical and Computational Applications of Strongly-Interacting Dynamics Beyond QCD
author_id_str_mv 427a653163238d69c8cf2c778bd59b07
author_id_fullname_str_mv 427a653163238d69c8cf2c778bd59b07_***_EDWARD BENNETT
author EDWARD BENNETT
author2 EDWARD BENNETT
format E-Thesis
publishDate 2013
institution Swansea University
doi_str_mv 10.23889/SUthesis.38186
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
active_str 0
description In this thesis we investigate numerically SU(2) theories with Dirac—or Majorana—fermions in the adjoint representation. Majorana fermions have historically proven difficult to treat numerically; here, a change of basis is introduced that allows two Majorana fermions to be expressed in terms of one Dirac fermion. This also provides greater insight into the analysis of the properties of theories with Dirac fermions. Attention is focused on the SU(2) theory with a single Dirac flavour (or equivalently two Majorana flavours). Its lattice phase diagram, spectrum, and the anomalous dimension of the chiral condensate are investigated. We observe a long region of constant mass ratios and an anomalous dimension 0.9 ≲ γ∗ ≲ 0.95. The behaviour of the pion mass and the presence of a light scalar in particular point to behaviour that is not traditionally confining; instead the theory appears to lie in or near the conformal window. The topological susceptibility and instanton size distribution are also investigated, for the one-Dirac-flavour theory and additionally the pure-gauge and two-Dirac-flavour (Minimal Walking Technicolor) theories. The properties are found to not depend on number of flavours, indicating a quenching of the fermions in the topology, also consistent with (near-)conformal behaviour (as has previously been reported in studies of other observables for Minimal Walking Technicolor). The code used is described, and a high-performance computing benchmark developed from it is detailed. While the benchmark was originally developed to investigate the performance of different supercomputer architectures for the class of problems we are interested in. Due to the nature of the code on which it is based, it has an unusual flexibility in the demands it may place on machine’s performance characteristics, which may allow it to be applicable to problems outside of lattice physics. The benchmark is used to characterise a number of machines’ relative performance.
published_date 2013-12-31T03:48:15Z
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score 11.036116

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