1992 Fiscal Year Final Research Report Summary
Loop calculations of superstring theory and string field theory
| Project/Area Number |
02640212
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
EZAWA Zyuniti Tohoku University, 理学部, 助教授 (90133925)
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| Co-Investigator(Kenkyū-buntansha) |
OKADA Yasuhiro 高エネルギー物理学研究所, 助教授 (20212334)
YOSHIMURA Motohiko 東北大学, 理学部, 教授 (70108447)
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| Project Period (FY) |
1990 – 1992
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| Keywords | superstring / topological excitation / fractional statistics / quantum Hall state / Josephson effect / grand unification theory / gravitational collapse / supergravity theory |
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| Research Abstract |
(1)Ezawa analyzed the superstring theory perturbatively by using covariantized Feynman-like rules known in the time of the dual resonance model. For this purpose, a new scheme was proposed to insert a certain projector into a propagator to take into account the so-called picture-changing operator. Based on the method the problem of finiteness of the superstring theory was discussed.
(2)Ezawa also analyzed the theory of anyons. Anyons are particles having fractional statistics peculiar to two-dimensional space. First, various properties of topological excitations (vortices) are studied in the anyon system. Then, constructing a field theory of anyons, a new method of analyzing the quantum Hall state in the planar electron system was proposed. By applying the scheme to a double-layer electron system, it was found that the Josephson effect should be observed at a certain Landau-level filling fraction. This implies a possibility of obtaining a new type of superconductivity in a system made of semiconductors. Furthermore, the observation of the Josephson effect turns out to determine the charge of the condensate of the quantum Hall state, which is claimed to be the elementary charge e.
(3)Yoshimura analyzed the two-demensional gravity as a prototype. The proposed model can be quantized semiclassically, and furthermore it can be solved explicitly. Using the solutions a concrete picture of a gravitational collapes is obtained.
(4)Superstring theory leads to certain supergravity or grand unified theories. Okada analyzed the quantum correction made on the Higgs mass through loop corrections due to top quarks and their superpartners in such a theory. A possibility of observing Higgs particles in near-future experiments was also discussed.
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