2020 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, 特任助教 (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 |
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| Outline of Annual Research Achievements |
The methods of effective field theory (EFT) construction from relativistic theories were extended to develop a new EFT that is able to describe a non-relativistic system - a solid. This relied on a technique for constructing a non-relativistic EFT from a fully relativistic EFT, treating the former as spontaneously breaking (some of) the symmetries of the latter. This technique was developed so as to deal with additional internal symmetries. The system described is a two-component solid, and redundancies between allowed operators resolved. A physical system that realises this symmetry breaking pattern was identified, namely bi-layer graphene (which recently has been under study due in connection with 'magic angle superconductivity). The resulting low-energy EFT is that of acoustic phonons along with what this work dubbed 'pseudo-acoustic' phonons. Already the potential application of this system to dark matter direct detection was highlighted; the interaction of pseudo-acoustic phonons could raise the scattering rate of dark matter by better satisfying energy-momentum conservation requirements.
The use of spinor helicity variables and their geometry was further elucidated, resulting in a novel way of describing the manifold upon which all possible particle interactions occur. This achieved a 'geometrizing' of observables in scattering experiments.
The mathematical machinery of Hilbert series, which solved a number of redundancy problems in EFT construction, was further developed by studying asymptotic formulae (corresponding to a high-temperature limit of the free theory).
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Already achieved a successful development of a novel EFT that can give insight into improving a rate of sub-MeV dark matter scattering in a detector. Some interesting mathematical avenues for investigating redundancies in operator bases was opened up.
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| Strategy for Future Research Activity |
Develop the asymptotic analysis of Hilbert series to analyse redundancies in EFT operator basis construction. Continue systematic studies of non-relativistic EFT construction.
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