2020 Fiscal Year Annual Research Report
繰り込み可能かつユニタリーな重力理論の探求：理論的・現象論的観点より
| Project/Area Number |
19F19324
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
山口 昌英 東京工業大学, 理学院, 教授 (80383511)
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| Co-Investigator(Kenkyū-buntansha) |
BUONINFANTE LUCA 東京工業大学, 理学院, 外国人特別研究員
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| Project Period (FY) |
2019-11-08 – 2022-03-31
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| Keywords | black hole |
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| Outline of Annual Research Achievements |
In the corpuscular picture of black hole there exists no geometric notion of horizon which, instead, only emerges in the semi-classical limit. Therefore, it is very natural to ask what happens if we send a signal towards a corpuscular black hole? With his collaborators, he has shown that quantum effects at the horizon scale imply the existence of a surface located at an effective radius slightly larger than the Schwarzschild radius. Consequently, the reflectivity of the object can be non-zero and, indeed, he finds that incoming waves with energies comparable to the Hawking temperature can have a probability of backscattering of order one. Thus, modes can be trapped between the two potential barriers located at the photon sphere and at the surface of a corpuscular black hole, and periodic echoes can be produced. The time delay of echoes turns out to be of the same order of the scrambling time. He has also shown that the compactness of a corpuscular black hole coincides with the quantum coupling that measures the interaction strength among gravitons, and discuss the physical implications of this remarkable feature.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
He has already obtained new good results.
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| Strategy for Future Research Activity |
During the final year of tenure, he is planning to investigate some phenomenological implications of such local and nonlocal field theories, especially in the context of gravity. Cosmological and astrophysical observations will be crucial in order to constrain their free parameters like the masses of extra degrees of freedom in local theories and/or the scale of nonlocality in nonlocal models. For instance, in view of the recent observation of gravitational wave emission, one of the first aims will be to compute for the first time the speed of the gravitational waves in the higher derivative models given above. and make a comparison with the current and future experimental data. He plans on travelling to discuss with other experts as well as to give presentations of his achievements.
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Research Products
(1 results)
