2023 Fiscal Year Annual Research Report
Effective field theory for sub-MeV dark matter direct detection
| Project/Area Number |
20H01896
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| Research Institution | The University of Tokyo |
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Principal Investigator |
Melia Thomas 東京大学, カブリ数物連携宇宙研究機構, 准教授 (30814909)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | effective field theory / sub-MeV dark matter / light dark matter |
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| Outline of Annual Research Achievements |
Effective field theory is a symmetry based approach to describing the relevant physics. In this project, the focus has been on non-relativistic effective field theories, and their synergy with dark matter detection. During FY2023 my research has identified a very unexpected story.
One of the key points of this research has been understanding how to systematically understand non-relativistic theories from the point of view of the relativistic theory, i.e. how they spontaneously break Lorentz symmetry. The generic rule is that in doing this one gets Goldstone bosons - e.g. phonons - which have universal properties, enabling a systematic approach. Goldstone's theorem seems unavoidable in this sense. What is very surprising is that my research has identified a way of breaking Lorentz symmetry without getting a Goldstone boson in the case of gauge theories of electromagnetism and general relativity. In two papers, my collaborators and I showed how a Lorentz-breaking choice of initial conditions for electric and gravitational field effectively behaves as if there is a background fluid of charge or matter, respectively. But these fluids strictly do not have phonons in them - Goldstone's theorem is evaded.
The reason is because of the gauge nature of the theories - both have constraint equations which can be relaxed. My work showed how this freedom manifests in the quantum theories.
Additionally, I investigated how the energy spectra of theories with an O(N) symmetry depend on N, and found new, non-perturbative constraints on the energy spectra of these theories.
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| Research Progress Status |
令和5年度が最終年度であるため、記入しない。
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| Strategy for Future Research Activity |
令和5年度が最終年度であるため、記入しない。
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