Aspects of BSM theories in the early universe
<p>The Standard Model (SM) of particle physics is a tremendously successful explanation of the nature we observe, both in Earth-based experiments and cosmological observations of the past history of the universe. However its failure to account for gravity, dark matter and dark energy, as well...
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| Format: | Thesis |
| Language: | English |
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2022
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| _version_ | 1826315801050742784 |
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| author | Tillim, H |
| author2 | March-Russell, J |
| author_facet | March-Russell, J Tillim, H |
| author_sort | Tillim, H |
| collection | OXFORD |
| description | <p>The Standard Model (SM) of particle physics is a tremendously successful explanation of the nature we observe, both in Earth-based experiments and cosmological observations of the past history of the universe. However its failure to account for gravity, dark matter and dark energy, as well as for various hierarchy and naturalness problems, motivates the formulation and investigation of Beyond-the-Standard-Model (BSM) theories.</p>
<p>In this thesis we will first review the evidence for and current understanding of dark matter (DM), including the mechanisms of freeze-out and freeze-in, before discussing the idea of ‘secluded’ dark matter without non-gravitational interactions with the SM. This will form the motivation for chapter 2, where we consider the emission of such secluded DM from an early population of primordial black holes, and for chapter 3, where we present a new mechanism by which an initially underpopulated secluded DM population may account for the observed DM in the universe today.</p>
<p>We will also discuss the hypothetical axion particle, which arises from an elegant so- lution to one of the problems with the SM (the Strong CP problem), and its generalisation, the Axion-Like-Particle (ALP). We will also introduce the one-dimensional topological defects called cosmic strings, and show how they can arise from ALP fields. ALPs serve as a candidate DM particle, and, further, are expected to appear in great numbers in the 4-dimensional effective theories arising from string theory (ST), a multiplicity known as the ‘string axiverse’. We shall review the foundations of ST with a focus on the creation of the string axiverse by the compactification of extra dimensions; finally in chapter 4 we construct global cosmic string solutions arising from string axiverse ALPs and analyse aspects of the resulting physics. In particular, we include the physically-crucial presence of a stabilising potential.</p> |
| first_indexed | 2024-03-07T07:28:24Z |
| format | Thesis |
| id | oxford-uuid:1ab59f14-e679-4484-94e3-4f0a1ee24863 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:32:51Z |
| publishDate | 2022 |
| record_format | dspace |
| spelling | oxford-uuid:1ab59f14-e679-4484-94e3-4f0a1ee248632024-12-01T15:59:20ZAspects of BSM theories in the early universeThesishttp://purl.org/coar/resource_type/c_db06uuid:1ab59f14-e679-4484-94e3-4f0a1ee24863AxionsDark matter (Astronomy)CosmologyString modelsEnglishHyrax Deposit2022Tillim, HMarch-Russell, JWest, SPetrossian-Byrne, R<p>The Standard Model (SM) of particle physics is a tremendously successful explanation of the nature we observe, both in Earth-based experiments and cosmological observations of the past history of the universe. However its failure to account for gravity, dark matter and dark energy, as well as for various hierarchy and naturalness problems, motivates the formulation and investigation of Beyond-the-Standard-Model (BSM) theories.</p> <p>In this thesis we will first review the evidence for and current understanding of dark matter (DM), including the mechanisms of freeze-out and freeze-in, before discussing the idea of ‘secluded’ dark matter without non-gravitational interactions with the SM. This will form the motivation for chapter 2, where we consider the emission of such secluded DM from an early population of primordial black holes, and for chapter 3, where we present a new mechanism by which an initially underpopulated secluded DM population may account for the observed DM in the universe today.</p> <p>We will also discuss the hypothetical axion particle, which arises from an elegant so- lution to one of the problems with the SM (the Strong CP problem), and its generalisation, the Axion-Like-Particle (ALP). We will also introduce the one-dimensional topological defects called cosmic strings, and show how they can arise from ALP fields. ALPs serve as a candidate DM particle, and, further, are expected to appear in great numbers in the 4-dimensional effective theories arising from string theory (ST), a multiplicity known as the ‘string axiverse’. We shall review the foundations of ST with a focus on the creation of the string axiverse by the compactification of extra dimensions; finally in chapter 4 we construct global cosmic string solutions arising from string axiverse ALPs and analyse aspects of the resulting physics. In particular, we include the physically-crucial presence of a stabilising potential.</p> |
| spellingShingle | Axions Dark matter (Astronomy) Cosmology String models Tillim, H Aspects of BSM theories in the early universe |
| title | Aspects of BSM theories in the early universe |
| title_full | Aspects of BSM theories in the early universe |
| title_fullStr | Aspects of BSM theories in the early universe |
| title_full_unstemmed | Aspects of BSM theories in the early universe |
| title_short | Aspects of BSM theories in the early universe |
| title_sort | aspects of bsm theories in the early universe |
| topic | Axions Dark matter (Astronomy) Cosmology String models |
| work_keys_str_mv | AT tillimh aspectsofbsmtheoriesintheearlyuniverse |