著者

Aoki Sinya Charron Bruno Doi Takumi Hatsuda Tetsuo Inoue Takashi Ishii Noriyoshi

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.87, no.3, pp.034512, 2013-02

被引用文献数

34 9

---

We construct energy-independent but nonlocal potentials above inelastic thresholds, in terms of Nambu-Bethe-Salpeter wave functions defined in quantum field theories such as QCD. As an explicit example, we consider NN→NN+nπ scattering processes for n=0,1,2,…. We show the existence of energy-independent coupled channel potentials with a nonrelativistic approximation, where momenta of all particles are small compared with their own masses. In the case of two-body inelastic scatterings such as ΛΛ→ΛΛ, NΞ, ΣΣ, on the other hand, we show that energy-independent potentials can be constructed without relying on nonrelativistic approximations. We also propose a method to extract these potentials using time dependence of general correlation functions.

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

Aoki Sinya Nagai Kei-ichi Taniguchi Yusuke Ukawa Akira

出版者

American Physical Society

雑誌

Physical review.D (ISSN:15507998)

巻号頁・発行日

vol.58, no.7, pp.074505, 1998-10

被引用文献数

44 90

---

We calculate one-loop renormalization factors of bilinear quark operators for the gluon action includingsix-link loops and an O(a)-improved quark action in the limit of a massless quark. We find that finite parts ofthe one-loop coefficients of renormalization factors diminish monotonically as either of the coefficients c1 orc21c3 of the six-link terms is decreased below zero. Detailed numerical results are given, for general valuesof the clover coefficient, for the tree-level improved gluon action in the Symanzik approach (c1521/12,c25c350) and for the choices suggested by Wilson (c1520.252,c250,c3520.17) and by Iwasaki (c1520.331,c25c350 and c1520.27,c21c3520.04) from renormalization-group analyses. Compared with thecase of the standard plaquette gluon action, the finite parts of the one-loop coefficients are reduced by 10–20 %for the Symanzik action, and approximately by a factor of 2 for the renormalization-group improved gluonactions.

著者

Aoki Sinya Balog Janos Weisz Peter

出版者

Springer

雑誌

Journal of high energy physics (ISSN:10298479)

巻号頁・発行日

vol.2010, no.5, pp.8, 2010-05

被引用文献数

11 17

---

We investigate the short distance behavior of nucleon-nucleon (NN) potentials defined through Bethe-Salpeter wave functions, by perturbatively calculating anomalous dimensions of 6-quark operators in QCD. Thanks to the asymptotic freedom of QCD, 1-loop computations give certain exact results for the potentials in the zero distance limit. In particular the functional form of the S-state central NN potential at short distance r is predicted to be a little weaker than r −2. On the other hand, due to the intriguing character of the anomalous dimension spectrum, perturbative considerations alone can not determine whether this potential is repulsive or attractive at short distances. A crude estimation suggests that the force at short distance is repulsive, as found numerically in lattice QCD. A similar behavior is found for the tensor potential.

著者

Kimura Taro Komatsu Shota Misumi Tatsuhiro Noumi Toshifumi Torii Shingo Aoki Sinya

出版者

Springer

雑誌

Journal of high energy physics (ISSN:10298479)

巻号頁・発行日

vol.2012, no.1, pp.048, 2012-01

被引用文献数

16

---

Employing the spin-flavor representation, we investigate the structures of the doubler-mixing symmetries and the mechanisms of their spontaneous breakdown in four types of lattice fermion formulation. We first revisit the U(4) × U(4) symmetries of the naive fermion with the vanishing bare mass m, and re-express them in terms of the spinflavor representation. We apply the same method to the Wilson fermion, which possesses only the U(1) vector symmetry for general values of m. For a special value of m, however, there emerges an additional U(1) symmetry to be broken by pion condensation. We also explore two types of minimally doubled fermion, and discover a similar kind of symmetry enhancement and its spontaneous breakdown.

著者

Aoki Sinya Balog Janos Weisz Peter

出版者

Springer

雑誌

Journal of high energy physics (ISSN:10298479)

巻号頁・発行日

no.9, pp.83, 2010-09

被引用文献数

7 13

---

The short distance behavior of baryon-baryon potentials defined throughNambu-Bethe-Salpeter wave functions is investigated using the operator product expansion.In a previous analysis of the nucleon-nucleon case, corresponding to the SU(3) channels27s and 10a, we argued that the potentials have a repulsive core. A new feature occursfor the case of baryons made up of three flavors: manifestly asymptotically attractive potentialsappear in the singlet and octet channels. Attraction in the singlet channel wasfirst indicated by quark model considerations, and recently been found in numerical latticesimulations. The latter have however not yet revealed asymptotic attraction in the octetchannels; we give a speculative explanation for this apparent discrepancy.

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.