Astro- and Quantum Physical Tests of Screened Scalar Fields
In general, modified gravity theories are modifications or extensions of Einstein's general relativity. Some of them give rise to additional scalar degrees of freedom in Nature. If these scalar fields exist and are light enough, they should cause a gravity-like fifth force that could, in princ...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English English |
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2019
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| Online Access: | https://eprints.nottingham.ac.uk/57180/ |
| _version_ | 1848799443981172736 |
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| author | Käding, Christian |
| author_facet | Käding, Christian |
| author_sort | Käding, Christian |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | In general, modified gravity theories are modifications or extensions of Einstein's general relativity. Some of them give rise to additional scalar degrees of freedom in Nature. If these scalar fields exist and are light enough, they should cause a gravity-like fifth force that could, in principle, exceed gravity in its strength. However, there are tight constraints on fifth forces from Solar System based tests. Screening mechanisms are popular means for avoiding these constraints by suppressing a fifth force in regions of high environmental mass density but allowing for phenomenologically interesting effects in environments of lower densities.
In this thesis, scalar field models with screening mechanisms will be discussed and some astro- and quantum physical tests for their existence presented. At first, the impact of disformally coupled symmetrons on gravitational lensing by galaxies will be evaluated. Secondly, it will be shown how fluctuations of a chameleon scalar field induce the open dynamics of a quantum test particle. For this, tools from non-equilibrium quantum field theory will be introduced, developed and applied, and a quantum master equation derived. |
| first_indexed | 2025-11-14T20:35:45Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-57180 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English English |
| last_indexed | 2025-11-14T20:35:45Z |
| publishDate | 2019 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-571802025-02-28T14:37:07Z https://eprints.nottingham.ac.uk/57180/ Astro- and Quantum Physical Tests of Screened Scalar Fields Käding, Christian In general, modified gravity theories are modifications or extensions of Einstein's general relativity. Some of them give rise to additional scalar degrees of freedom in Nature. If these scalar fields exist and are light enough, they should cause a gravity-like fifth force that could, in principle, exceed gravity in its strength. However, there are tight constraints on fifth forces from Solar System based tests. Screening mechanisms are popular means for avoiding these constraints by suppressing a fifth force in regions of high environmental mass density but allowing for phenomenologically interesting effects in environments of lower densities. In this thesis, scalar field models with screening mechanisms will be discussed and some astro- and quantum physical tests for their existence presented. At first, the impact of disformally coupled symmetrons on gravitational lensing by galaxies will be evaluated. Secondly, it will be shown how fluctuations of a chameleon scalar field induce the open dynamics of a quantum test particle. For this, tools from non-equilibrium quantum field theory will be introduced, developed and applied, and a quantum master equation derived. 2019-12-13 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en arr https://eprints.nottingham.ac.uk/57180/1/Thesis.pdf application/pdf en arr https://eprints.nottingham.ac.uk/57180/7/Thesis.pdf Käding, Christian (2019) Astro- and Quantum Physical Tests of Screened Scalar Fields. PhD thesis, University of Nottingham. general relativity scalar fields quantum field theory |
| spellingShingle | general relativity scalar fields quantum field theory Käding, Christian Astro- and Quantum Physical Tests of Screened Scalar Fields |
| title | Astro- and Quantum Physical Tests of Screened Scalar Fields |
| title_full | Astro- and Quantum Physical Tests of Screened Scalar Fields |
| title_fullStr | Astro- and Quantum Physical Tests of Screened Scalar Fields |
| title_full_unstemmed | Astro- and Quantum Physical Tests of Screened Scalar Fields |
| title_short | Astro- and Quantum Physical Tests of Screened Scalar Fields |
| title_sort | astro- and quantum physical tests of screened scalar fields |
| topic | general relativity scalar fields quantum field theory |
| url | https://eprints.nottingham.ac.uk/57180/ |