E-Thesis 340 views 541 downloads
Calculation of graviton scattering amplitudes using new techniques / Paul Stephen Norridge
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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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Swansea
2021
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa58570 |
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| 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 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. |
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| College: |
Faculty of Science and Engineering |