models:speculative_models:axion
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models:speculative_models:axion [2018/03/26 15:17] jakobadmin [Intuitive] |
models:speculative_models:axion [2019/07/01 09:24] jakobadmin [Criticism] |
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| - | ====== Axion Theories ====== | + | ====== Axion Models ====== |
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| <tabbox Concrete> | <tabbox Concrete> | ||
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| + | * A really great and short introduction is [[https://www.sciencedirect.com/science/article/pii/S1631070511002039|The strong CP problem by Pierre Sikivie]] | ||
| * [[https://arxiv.org/abs/1712.03018|Axions and ALPs: a very short introduction]] by David J. E. Marsh | * [[https://arxiv.org/abs/1712.03018|Axions and ALPs: a very short introduction]] by David J. E. Marsh | ||
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| <tabbox Why is it interesting?> | <tabbox Why is it interesting?> | ||
| - | Axions are proposed as a solution to the [[open_problems:strong_cp_problem|strong CP problem]]. In some sense, it's the simplest solution, because the QCD vacuum energy has a minimum at $\bar{\theta}=0$ and the axion allows the vacuum to relax to this ground state. Without the axion the QCD vacuum is frozen and $\bar{\theta}$ is therefore fixed at some not-necessarily minimum value. | + | Axions are proposed as a solution to the [[open_problems:strong_cp_puzzle|strong CP problem]]. In some sense, it's the simplest solution, because the QCD vacuum energy has a minimum at $\bar{\theta}=0$ and the axion allows the vacuum to relax to this ground state. Without the axion the QCD vacuum is frozen and $\bar{\theta}$ is therefore fixed at some not-necessarily minimum value. |
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| <tabbox History> | <tabbox History> | ||
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| <cite>[[https://arxiv.org/pdf/1608.08969.pdf|Domestic Axion]] Gia Dvali</cite> | <cite>[[https://arxiv.org/pdf/1608.08969.pdf|Domestic Axion]] Gia Dvali</cite> | ||
| </blockquote> | </blockquote> | ||
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| + | <blockquote>The notion of Peccei–Quinn (PQ) symmetry may seem contrived. Why should there be a U(1) symmetry which is broken at the quantum level but which is exact at the classical level? However, the reason for PQ symmetry may be deeper than we know at present. String theory contains many examples of symmetries which are exact classically but which are broken by quantum anomalies, including PQ symmetry [17–19]. Within field theory, there are examples of theories with automatic PQ symmetry, i.e. where PQ symmetry is a consequence of just the particle content of the theory without adjustment of parameters to special values. <cite>[[https://www.sciencedirect.com/science/article/pii/S1631070511002039|The strong CP problem by Pierre Sikivie]]</cite></blockquote> | ||
| </tabbox> | </tabbox> | ||
models/speculative_models/axion.txt · Last modified: 2019/07/01 09:27 by jakobadmin
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