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Norikazu Yamada

Bio: Norikazu Yamada is an academic researcher from KEK. The author has contributed to research in topics: Quantum chromodynamics & Unitarity. The author has an hindex of 2, co-authored 2 publications receiving 28 citations.

Papers
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Journal ArticleDOI
Norikazu Yamada1
01 May 2003
TL;DR: In this paper, the authors discuss the lattice determination of the B-B mixing amplitude and how to put a strong constraint on the poorly known CKM element |Vtd| and other important quantities such as form factors of semi-leptonic decays.
Abstract: Precise knowledge onB meson decay properties plays an essential role in testing the unitarity of the CKM matrix [1,2]. The experimental status relevant to the unitarity test is now promising because experimental uncertainties are already very small or expected to be reduced well in the near future [3]. On the other hand, theoretical calculations relevant to the test are still not sufficiently accurate due to the non-perturbative effect of QCD. Lattice QCD is an ideal tool to deal with this effect and should be able to reduce the current theoretical uncertainties [4]. Apart from the asymmetric ee colliders, there are two important upcoming experiments for the unitarity test. The Tevatron Run II will produce a large number of and variety of b and chadrons, and their basic properties such as mass and lifetime will be precisely measured [5]. What is important for us is that once B s -B 0 s mixing is observed the mass difference ∆MBs will be measured with a few percent accuracy. The width difference in the Bs meson system is also expected to be measured precisely. Another exciting experiment is the CLEO-c project [6]. There, charmed quarkonia, hybrid states and glueballs will be observed. In particular the leptonic and the semileptonic decays of D mesons are expected to be measured with a few percent level. Advancing lattice QCD calculations with a view to combining them with these precise experimental results is an urgent task in front of us. In this review, I will focus on new and updated calculations of hadron matrix elements. The current status and progress made in spectrum calculations and formulations are not covered, although they are very important and interesting. In particular, I will mainly discuss the lattice determination of the B-B mixing amplitude and how to put a strong constraint on the poorly known CKM element |Vtd|. The other important quantities such as form factors of semi-leptonic decays will be mentioned briefly. Recently several suggestions to improve the limits on accuracy of present lattice calculations have been made in methodology. I will briefly introduce some of them before summarizing my point of view on the current status.

19 citations

Journal ArticleDOI
Norikazu Yamada1
TL;DR: In this paper, the authors discuss the lattice determination of the B-B mixing amplitude and how to put a strong constraint on the poorly known CKM element |Vtd| and other important quantities such as form factors of semi-leptonic decays.
Abstract: Precise knowledge onB meson decay properties plays an essential role in testing the unitarity of the CKM matrix [1,2]. The experimental status relevant to the unitarity test is now promising because experimental uncertainties are already very small or expected to be reduced well in the near future [3]. On the other hand, theoretical calculations relevant to the test are still not sufficiently accurate due to the non-perturbative effect of QCD. Lattice QCD is an ideal tool to deal with this effect and should be able to reduce the current theoretical uncertainties [4]. Apart from the asymmetric ee colliders, there are two important upcoming experiments for the unitarity test. The Tevatron Run II will produce a large number of and variety of b and chadrons, and their basic properties such as mass and lifetime will be precisely measured [5]. What is important for us is that once B s -B 0 s mixing is observed the mass difference ∆MBs will be measured with a few percent accuracy. The width difference in the Bs meson system is also expected to be measured precisely. Another exciting experiment is the CLEO-c project [6]. There, charmed quarkonia, hybrid states and glueballs will be observed. In particular the leptonic and the semileptonic decays of D mesons are expected to be measured with a few percent level. Advancing lattice QCD calculations with a view to combining them with these precise experimental results is an urgent task in front of us. In this review, I will focus on new and updated calculations of hadron matrix elements. The current status and progress made in spectrum calculations and formulations are not covered, although they are very important and interesting. In particular, I will mainly discuss the lattice determination of the B-B mixing amplitude and how to put a strong constraint on the poorly known CKM element |Vtd|. The other important quantities such as form factors of semi-leptonic decays will be mentioned briefly. Recently several suggestions to improve the limits on accuracy of present lattice calculations have been made in methodology. I will briefly introduce some of them before summarizing my point of view on the current status.

9 citations


Cited by
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Proceedings ArticleDOI
23 Aug 1992
TL;DR: Mes premiers remtrciements trout aux auteurs des 206 communications th6matiquts et notes de projet, sans qui ces actes n'auraient 6videmment pas vu le jour.
Abstract: Mes premiers remtrciements trout aux auteurs des 206 communications th6matiquts et notes de projet, sans qui ces actes n'auraient 6videmment pas vu le jour. / Is oat contribu6 h la qualit6 scientifique et ,5 I'hmuog6t~6it6 pr6sentationntlle de leurs articles en refondant les versions iuitiales soumises an comit6 de programme, ea acceptant de suivre les r~gles de pr6sentation indiqu6es, et en nous envoyant parrots plusieurs versions am61ior6es surun point ou sur l'autrc.

824 citations

01 Jan 1990
TL;DR: A nonrelativistic reformulation of the heavy-quark dynamics that is systematically developed starting from the Dirac theory is presented, far superior to traditional relativistic techniques, as illustrated in a numerical study of the $\ensuremath{\Upsilon}$ and $psi$ meson families.
Abstract: We present a new technique for analyzing heavy-quark bound states in lattice QCD. The method is based upon a nonrelativistic reformulation of the heavy-quark dynamics that is systematically developed starting from the Dirac theory. It is far superior to traditional relativistic techniques, as we illustrate in a numerical study of the $\ensuremath{\Upsilon}$ and $\ensuremath{\psi}$ meson families.

163 citations

Journal ArticleDOI
TL;DR: In this article, a simple model based on the extended technicolor (ETC) group SU(5) was constructed and analyzed, which leads to non-trivial but not realistic mixing angles in the quark and lepton sectors.
Abstract: We study fermion masses and mixing angles, including the generation of a seesaw mechanism for the neutrinos, in extended technicolor (ETC) theories. We formulate an approach to these problems that relies on assigning right-handed $Q=-1/3$ quarks and charged leptons to ETC representations that are conjugates of those of the corresponding left-handed fermions. This leads to a natural suppression of these masses relative to the $Q=2/3$ quarks, as well as the generation of quark mixing angles, both long-standing challenges for ETC theories. Standard-model-singlet neutrinos are assigned to ETC representations that provide a similar suppression of neutrino Dirac masses, as well as the possibility of a realistic seesaw mechanism with no mass scale above the highest ETC scale of roughly $10^3$ TeV. A simple model based on the ETC group SU(5) is constructed and analyzed. This model leads to non-trivial, but not realistic mixing angles in the quark and lepton sectors. It can also produce sufficiently light neutrinos, although not simultaneously with a realistic quark spectrum. We discuss several aspects of the phenomenology of this class of models.

125 citations

Journal ArticleDOI
TL;DR: In this paper, the problem of the subtraction of power-law divergences is solved by a non-perturbative matching of HQET and QCD on the lattice.
Abstract: We explain how to perform non-perturbative computations in HQET on the lattice. In particular the problem of the subtraction of power-law divergences is solved by a non-perturbative matching of HQET and QCD. As examples, we present a full calculation of the mass of the b-quark in the combined static and quenched approximation and outline an alternative way to obtain the B-meson decay constant at lowest order. Since no excessively large lattices are required, our strategy can also be applied including dynamical fermions.

108 citations

Journal ArticleDOI
TL;DR: The anomalous dimension of the heavy-light quark current in HQET was calculated with three-loop accuracy, as well as the renormalized heavy-quark propagator as mentioned in this paper.

87 citations