- 著者
- Aoki Sinya Fukaya Hidenori Hashimoto Shoji Onogi Tetsuya
- 出版者
- American Physical Society
- 雑誌
- Physical review D (ISSN:15507998)
- 巻号頁・発行日
- vol.76, no.5, pp.054508, 2007-09
- 被引用文献数
- 85 93
In finite volume the partition function of QCD with a given theta is a sum of different topological sectors with a weight primarily determined by the topological susceptibility. If a physical observable is evaluated only in a fixed topological sector, the result deviates from the true expectation value by an amount proportional to the inverse space-time volume 1/V. Using the saddle point expansion, we derive formulas to express the correction due to the fixed topological charge in terms of a 1/V expansion. Applying this formula, we propose a class of methods to determine the topological susceptibility in QCD from various correlation functions calculated in a fixed topological sector.
- 著者
- Feng Xu Aoki Sinya Fukaya Hidenori Hashimoto Shoji Kaneko Takashi Noaki Jun-ichi Shintani Eigo JLQCD Collaboration
- 出版者
- American Physical Society
- 雑誌
- Physical Review Letters (ISSN:00319007)
- 巻号頁・発行日
- vol.109, no.18, pp.182001, 2012-11
- 被引用文献数
- 20 8
We perform a nonperturbative calculation of the π0→γγ transition form factor and the associated decay width using lattice QCD. The amplitude for a two-photon final state, which is not an eigenstate of QCD, is extracted through a Euclidean time integral of the relevant three-point function. We utilize the all-to-all quark propagator technique to carry out this integration as well as to include the disconnected quark diagram contributions. The overlap fermion formulation is employed on the lattice to ensure exact chiral symmetry on the lattice. After examining various sources of systematic effects, except for a possible discretization effect, we obtain Γπ0→γγ=7.83(31)(49) eV for the pion decay width, where the first error is statistical and the second is our estimate of the systematic error.