2007 Fiscal Year Final Research Report Summary
Theoretical Analysis of Heavy Quarkonia and Determination of Fundamental Paysical Constants
| Project/Area Number |
17540228
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Tohoku University |
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Principal Investigator |
SUMINO Yukinari Tohoku University, Tohoku Univ., Groduate School of Sci.,, Research Ass. (80260412)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Perturbative QCD / Quarkonium / QCD Potential / Higher-order correction / Renormalon |
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| Research Abstract |
Following the theoretical breakthrough around 1998, possibility to predict physical quantities of heavy quarkonium systems based on perturbative QCD opened up. On the basis of this progress, we proposed the following research projects: (1) We determine the fundamental physical constants, such as the strong coupling constant α_S(M_Z) or the MS masses of heavy quarks, using precision theoretical predictions of the spectra of heavy quarkonium states. (2) We develop our understandings of heavy quarkonium systems in terms of microscopic theory. According to these individual objectives, we obtained the following research achievements: (a) Combining the recent predictions for the perturbative QCD potential, lattice results, and the operator-product expansion, we showed that α_S(M_Z) can be determined accurately. In fact, using the recent precision lattice result, we determined α_S in quenched approximation. Furthermore, this method seems promising for determination of α_S(M_Z) in the future. (b) We computed QCD radiative corrections to pair-annihilation of neutralino in early universe. We also computed top quark production cross section near threshold at LHC. In both of these processes, the tt resonances play important roles, and our theoretical framework of quarkonium systems turned out to be useful in the computations. (c) In the computation of 3-loop corrections to the QCD potential, we reduced a huge number of Feynman integrals to a small set of master integrals, thereby progressing the computation significantly. Perfection of this computation will lead to precision determination of α_S(M_Z) and heavy quark masses.
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