著者

Noaki J. Aoki S. Aoki Y. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Izubuchi T. Kanaya K. Kaneko T. Kuramashi Y. Lesk V. Nagai K. I. Okawa M. Taniguch Y. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.68, no.1, pp.014501, 2003-07

被引用文献数

45 146

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We explore the application of the domain wall fermion formalism of lattice QCD to calculate the K→ππ decay amplitudes in terms of the K+→π+ and K0→0 hadronic matrix elements through relations derived in chiral perturbation theory. Numerical simulations are carried out in quenched QCD using the domain-wall fermion action for quarks and a renormalization group-improved gauge action for gluons on a 163×32×16 and 243×32×16 lattice at β=2.6 corresponding to the lattice spacing 1/a≈2 GeV. Quark loop contractions which appear in Penguin diagrams are calculated by the random noise method, and the ΔI=1/2 matrix elements which require subtractions with the quark loop contractions are obtained with a statistical accuracy of about 10%. We investigate the chiral properties required of the K+→π+ matrix elements. Matching the lattice matrix elements to those in the continuum at μ=1/a using the perturbative renormalization factor to one loop order, and running to the scale μ=mc=1.3 GeV with the renormalization group for Nf=3 flavors, we calculate all the matrix elements needed for the decay amplitudes. With these matrix elements, the ΔI=3/2 decay amplitude Re A2 shows a good agreement with experiment after an extrapolation to the chiral limit. The ΔI=1/2 amplitude Re A0, on the other hand, is about 50–60 % of the experimental one even after chiral extrapolation. In view of the insufficient enhancement of the ΔI=1/2 contribution, we employ the experimental values for the real parts of the decay amplitudes in our calculation of ɛ′/ɛ. The central values of our result indicate that the ΔI=3/2 contribution is larger than the ΔI=1/2 contribution so that ɛ′/ɛ is negative and has a magnitude of order 10-4. We discuss in detail possible systematic uncertainties, which seem too large for a definite conclusion on the value of ɛ′/ɛ.

著者

Khan A. Ali Aoki S. Aoki Y. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Izubuchi T. Kanaya K. Kaneko T. Kuramashi Y. Nagai K. I. Okawa M. Shanahan H. P. Taniguchi Y. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.64, no.11, pp.114506, 2001-11

被引用文献数

43 91

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We report on a calculation of BK with domain-wall fermion action in quenched QCD. Simulations are made with a renormalization group improved gauge action at β=2.6 and 2.9 corresponding to a-1≈2 and 3 GeV. Effects due to finite fifth dimensional size N5 and finite spatial size Nσ are examined in detail. Matching to the continuum operator is made perturbatively at one loop order. We obtain BK(μ=2 GeV)=0.5746(61)(191), where the first error is statistical and the second error represents an estimate of scaling violation and O(α2) errors in the renormalization factor added in quadrature, as an estimate of the continuum value in the modified minimal subtraction (MS̅ ) scheme with naive dimensional regularization. This value is consistent, albeit somewhat small, with BK(μ=2 GeV)=0.628(42) obtained by the JLQCD Collaboration using the Kogut-Susskind quark action. Results for light quark masses are also reported.

著者

Khan A. Ali Aoki S. Aoki Y. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Izubuchi T. Kanaya K. Kaneko T. Kuramashi Y. Manke T. Nagai K. I. Noaki J. Okawa M. Shanahan H. P. Taniguchi Y. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.63, no.11, pp.114504, 2001-05

被引用文献数

47 61

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We investigate the chiral properties of quenched domain-wall QCD (DWQCD) at the lattice spacings a-1≃1 and 2 GeV for both plaquette and renormalization-group (RG) improved gauge actions. In the case of the plaquette action we find that the quark mass defined through the axial Ward-Takahashi identity remains non-vanishing in the DWQCD chiral limit that the bare quark mass mf→0 and the length of the fifth dimension Ns→∞, indicating that chiral symmetry is not realized with quenched DWQCD up to a-1≃2 GeV. The behavior is much improved for the RG-improved gauge action: while a nonvanishing quark mass remains in the chiral limit at a-1≃1 GeV, the result at a-1≃2 GeV is consistent with an exponentially vanishing quark mass in the DWQCD chiral limit, indicating the realization of exact chiral symmetry. An interpretation and implications are briefly discussed.