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Calculation of graviton scattering amplitudes using new techniques / Paul Stephen Norridge

DOI (Published version): 10.23889/SUthesis.58570

Abstract

The calculations of scattering amplitudes in gauge theories are well-known for the difficulties which they present. Traditional methods for obtaining perturbative results (e.g. Feynman diagrams) are often impractical in all but the simplest cases. This has led to searches for new techniques which si...

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Published: Swansea 2021
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa58570
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first_indexed 2021-11-08T10:57:55Z
last_indexed 2021-11-09T04:25:59Z
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spelling 2021-11-08T11:28:33.9719144 v2 58570 2021-11-08 Calculation of graviton scattering amplitudes using new techniques 2021-11-08 The calculations of scattering amplitudes in gauge theories are well-known for the difficulties which they present. Traditional methods for obtaining perturbative results (e.g. Feynman diagrams) are often impractical in all but the simplest cases. This has led to searches for new techniques which simplify the calculational process and allow a wider set of results to be obtained. In recent years these searches have produced a number of new methods which have been used successfully to find many amplitudes in QCD. Scattering amplitudes in perturbative quantum gravity are among the most difficult to calculate. The success of the new techniques in the standard model scenario suggests that it would be profitable to look at extensions of these to PQG. Here we look at the ways in which two of these methods - the string-inspired and Cutkosky rules - can be applied in the new situation. We show how a set of string-inspired rules for one-loop graviton amplitudes can be derived by looking at a closed bosonic string and how we can use information provided by the Cutkosky method. As an example of the string-inspired technique we calculate all one-loop four graviton amplitudes with massless internal particles. An application of the Cutkosky rules allows us to check these results as well as to obtain information about divergences in PQG theories. A combination of the Cutkosky rules and dimensional reduction enables us to re-derive some of the string-based results and to extend these to cases with massive internal particles. E-Thesis Swansea 8 11 2021 2021-11-08 10.23889/SUthesis.58570 COLLEGE NANME COLLEGE CODE Swansea University Doctoral Ph.D 2021-11-08T11:28:33.9719144 2021-11-08T10:42:57.2035622 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics Paul Stephen Norridge 1 58570__21444__63264e09e12940979a29834dc8e5109a.pdf Norridge_Paul_S_PhD_Thesis_Final.pdf 2021-11-08T11:13:36.5967850 Output 9217843 application/pdf E-Thesis – open access true true eng
title Calculation of graviton scattering amplitudes using new techniques
spellingShingle Calculation of graviton scattering amplitudes using new techniques
,
title_short Calculation of graviton scattering amplitudes using new techniques
title_full Calculation of graviton scattering amplitudes using new techniques
title_fullStr Calculation of graviton scattering amplitudes using new techniques
title_full_unstemmed Calculation of graviton scattering amplitudes using new techniques
title_sort Calculation of graviton scattering amplitudes using new techniques
author ,
author2 Paul Stephen Norridge
format E-Thesis
publishDate 2021
institution Swansea University
doi_str_mv 10.23889/SUthesis.58570
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 The calculations of scattering amplitudes in gauge theories are well-known for the difficulties which they present. Traditional methods for obtaining perturbative results (e.g. Feynman diagrams) are often impractical in all but the simplest cases. This has led to searches for new techniques which simplify the calculational process and allow a wider set of results to be obtained. In recent years these searches have produced a number of new methods which have been used successfully to find many amplitudes in QCD. Scattering amplitudes in perturbative quantum gravity are among the most difficult to calculate. The success of the new techniques in the standard model scenario suggests that it would be profitable to look at extensions of these to PQG. Here we look at the ways in which two of these methods - the string-inspired and Cutkosky rules - can be applied in the new situation. We show how a set of string-inspired rules for one-loop graviton amplitudes can be derived by looking at a closed bosonic string and how we can use information provided by the Cutkosky method. As an example of the string-inspired technique we calculate all one-loop four graviton amplitudes with massless internal particles. An application of the Cutkosky rules allows us to check these results as well as to obtain information about divergences in PQG theories. A combination of the Cutkosky rules and dimensional reduction enables us to re-derive some of the string-based results and to extend these to cases with massive internal particles.
published_date 2021-11-08T04:15:12Z
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score 11.013619

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