Tetsuya Onogi
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Tetsuya Onogi has a total of 26 co-authors. Here are the top co-authors by number of shared publications:
- Hideo Matsufuru
High Energy Accelerator Research Organization
10 shared publications - Hiroshi Ohki
Yukawa Institute for Theoretical Physics Kyoto University 606-8502 Kyoto Japan
5 shared publications - Shoji Hashimoto
KEK Theory Center, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
4 shared publications - Masafumi Kurachi
Department of Physics, Tohoku University, Sendai 980-8578, Japan
3 shared publications - Antonino Flachi
Keio University
2 shared publications - Erek Bilgici
Institut für Physik Universität Graz A-8010 Graz Austria
2 shared publications
Latest Publications
- 1 January 2011
- Published by Oxford University Press (OUP) in Progress of Theoretical Physics
- Vol. 125 (1) , 103-128
Flavor Structure of the Three Site Higgsless Model
We study the flavor structure in the three site Higgsless model. In this model, the gauge bosons and fermions have heavy partners, coming from the Kaluza-Klein excitation in the dimensional deconstruction picture. The Yukawa couplings are introduced in a way to minimize the flavor-changing neutral current (FCNC) in the light sector at the tree level. Owing to the flavor mixing between the light and heavy partner fields, new effects on FCNCs appear at the one-loop level. As an example of such FCNC processes, we calculate the contribution to the b → sγ amplitude in the three site Higgsless model. Interestingly, heavy particles that exist in the three site Higgsless model do not completely decouple in the heavy-mass limit. The one-loop level b → sγ amplitude is calculated by considering all possible combinations of particles in the loop; then, it is compared with the experiment. The result shows that the central value of the B → X s γ branching ratio in the three site Higgsless model is closer to its experimental central value as one takes the larger value of a free parameter, ε tR , within a range allowed by the precision electroweak measurement.
- 1 January 2011
- Published by Oxford University Press (OUP) in Progress of Theoretical Physics
- Vol. 125 (1) , 103-128
Flavor Structure of the Three Site Higgsless Model
We study the flavor structure in the three site Higgsless model. In this model, the gauge bosons and fermions have heavy partners, coming from the Kaluza-Klein excitation in the dimensional deconstruction picture. The Yukawa couplings are introduced in a way to minimize the flavor-changing neutral current (FCNC) in the light sector at the tree level. Owing to the flavor mixing between the light and heavy partner fields, new effects on FCNCs appear at the one-loop level. As an example of such FCNC processes, we calculate the contribution to the b → sγ amplitude in the three site Higgsless model. Interestingly, heavy particles that exist in the three site Higgsless model do not completely decouple in the heavy-mass limit. The one-loop level b → sγ amplitude is calculated by considering all possible combinations of particles in the loop; then, it is compared with the experiment. The result shows that the central value of the B → X s γ branching ratio in the three site Higgsless model is closer to its experimental central value as one takes the larger value of a free parameter, ε tR , within a range allowed by the precision electroweak measurement.
- Open Access
A new scheme for the running coupling constant in gauge theories using Wilson loops
We propose a new renormalization scheme of the running coupling constant in general gauge theories using the Wilson loops. The renormalized coupling constant is obtained from the Creutz ratio in lattice simulations and the corresponding perturbative coefficient at the leading order. The latter can be calculated by adopting the zeta-function resummation techniques. We perform a benchmark test of our scheme in quenched QCD with the plaquette gauge action. The running of the coupling constant is determined by applying the step-scaling procedure. Using several methods to improve the statistical accuracy, we show that the running coupling constant can be determined in a wide range of energy scales with relatively small number of gauge configurations.
Open AccessA new scheme for the running coupling constant in gauge theories using Wilson loops
We propose a new renormalization scheme of the running coupling constant in general gauge theories using the Wilson loops. The renormalized coupling constant is obtained from the Creutz ratio in lattice simulations and the corresponding perturbative coefficient at the leading order. The latter can be calculated by adopting the zeta-function resummation techniques. We perform a benchmark test of our scheme in quenched QCD with the plaquette gauge action. The running of the coupling constant is determined by applying the step-scaling procedure. Using several methods to improve the statistical accuracy, we show that the running coupling constant can be determined in a wide range of energy scales with relatively small number of gauge configurations.
- 31 August 2009
- Published by American Physical Society (APS) in Physical Review D
- Vol. 80 (3) , 034507
New scheme for the running coupling constant in gauge theories using Wilson loops
We propose a new renormalization scheme of the running coupling constant in general gauge theories using the Wilson loops. The renormalized coupling constant is obtained from the Creutz ratio in lattice simulations and the corresponding perturbative coefficient at the leading order. The latter can be calculated by adopting the zeta-function resummation techniques. We perform a benchmark test of our scheme in quenched QCD with the plaquette gauge action. The running of the coupling constant is determined by applying the step-scaling procedure. Using several methods to improve the statistical accuracy, we show that the running coupling constant can be determined in a wide range of energy scales with a relatively small number of gauge configurations.
- 31 August 2009
- Published by American Physical Society (APS) in Physical Review D
- Vol. 80 (3) , 034507
New scheme for the running coupling constant in gauge theories using Wilson loops
We propose a new renormalization scheme of the running coupling constant in general gauge theories using the Wilson loops. The renormalized coupling constant is obtained from the Creutz ratio in lattice simulations and the corresponding perturbative coefficient at the leading order. The latter can be calculated by adopting the zeta-function resummation techniques. We perform a benchmark test of our scheme in quenched QCD with the plaquette gauge action. The running of the coupling constant is determined by applying the step-scaling procedure. Using several methods to improve the statistical accuracy, we show that the running coupling constant can be determined in a wide range of energy scales with a relatively small number of gauge configurations.
- 28 May 2008
- Published by American Physical Society (APS) in Physical Review D
- Vol. 77 (9)
Determination ofcoupling in unquenched lattice QCDThe coupling is a fundamental parameter of chiral effective Lagrangian with heavy-light mesons and can constrain the chiral behavior of , , and the form factor in the soft pion limit. We compute the coupling with the static heavy quark and the -improved Wilson light quark. Simulations are carried out with unquenched lattices at and lattices at generated by the CP-PACS collaboration. To improve the statistical accuracy, we employ the all-to-all propagator technique and the static quark action with smeared temporal link variables. These methods successfully work also on unquenched lattices, and determine the coupling with 1%–2% statistical accuracy on each lattice spacing. DOI: http://dx.doi.org/10.1103/PhysRevD.77.094509 © 2008 The American Physical Society- 28 May 2008
- Published by American Physical Society (APS) in Physical Review D
- Vol. 77 (9)
Determination ofcoupling in unquenched lattice QCDThe coupling is a fundamental parameter of chiral effective Lagrangian with heavy-light mesons and can constrain the chiral behavior of , , and the form factor in the soft pion limit. We compute the coupling with the static heavy quark and the -improved Wilson light quark. Simulations are carried out with unquenched lattices at and lattices at generated by the CP-PACS collaboration. To improve the statistical accuracy, we employ the all-to-all propagator technique and the static quark action with smeared temporal link variables. These methods successfully work also on unquenched lattices, and determine the coupling with 1%–2% statistical accuracy on each lattice spacing. DOI: http://dx.doi.org/10.1103/PhysRevD.77.094509 © 2008 The American Physical Society- Open Access
Determination of B*B pi coupling in unquenched QCD
The $B^* B\pi$ coupling is a fundamental parameter of chiral effective Lagrangian with heavy-light mesons and can constrain the chiral behavior of $f_B$, $B_B$ and the $B\to \pi l \nu$ form factor in the soft pion limit. We compute the $B^* B \pi $ coupling with the static heavy quark and the $O(a)$-improved Wilson light quark. Simulations are carried out with $n_f=2$ unquenched $12^3\times 24$ lattices at $\beta=1.80$ and $16^3\times 32$ lattices at $\beta=1.95$ generated by CP-PACS collaboration. To improve the statistical accuracy, we employ the all-to-all propagator technique and the static quark action with smeared temporal link variables following the quenched study by Negishi {\it et al.}. These methods successfully work also on unquenched lattices, and determine the $B^*B\pi$ coupling with 1--2% statistical accuracy on each lattice spacing.Open AccessDetermination of B*B pi coupling in unquenched QCD
The $B^* B\pi$ coupling is a fundamental parameter of chiral effective Lagrangian with heavy-light mesons and can constrain the chiral behavior of $f_B$, $B_B$ and the $B\to \pi l \nu$ form factor in the soft pion limit. We compute the $B^* B \pi $ coupling with the static heavy quark and the $O(a)$-improved Wilson light quark. Simulations are carried out with $n_f=2$ unquenched $12^3\times 24$ lattices at $\beta=1.80$ and $16^3\times 32$ lattices at $\beta=1.95$ generated by CP-PACS collaboration. To improve the statistical accuracy, we employ the all-to-all propagator technique and the static quark action with smeared temporal link variables following the quenched study by Negishi {\it et al.}. These methods successfully work also on unquenched lattices, and determine the $B^*B\pi$ coupling with 1--2% statistical accuracy on each lattice spacing. - Open Access
High precision study of B*B pi coupling in unquenched QCD
The B* B pi coupling is a fundamental parameter of chiral effective Lagrangian with heavy-light mesons and can constrain the B->pi l nu form factor in the soft pion limit which will be useful for precise determination of |Vub|. We compute the B* B pi coupling with the static heavy quark and the O(a)-improved Wilson light quark. Simulations are carried out with n_f=2 unquenched 12^3x24 lattices at beta=1.80 generated by CP-PACS collaboration. Following the quenched study by Negishi et al., we employ the all-to-all propagator with 200 low eigenmodes as well as HYP smeared link to improve the statistical accuracy.
Open AccessHigh precision study of B*B pi coupling in unquenched QCD
The B* B pi coupling is a fundamental parameter of chiral effective Lagrangian with heavy-light mesons and can constrain the B->pi l nu form factor in the soft pion limit which will be useful for precise determination of |Vub|. We compute the B* B pi coupling with the static heavy quark and the O(a)-improved Wilson light quark. Simulations are carried out with n_f=2 unquenched 12^3x24 lattices at beta=1.80 generated by CP-PACS collaboration. Following the quenched study by Negishi et al., we employ the all-to-all propagator with 200 low eigenmodes as well as HYP smeared link to improve the statistical accuracy.
- Open Access
Theta vacuum physics from QCD at fixed topology
We propose a method to obtain physical quantities in the theta vacuum from those at fixed topology, which are different by finite size effects. Extending the work by Brower et al., we derive the formula to estimate these finite size corrections for arbitrary correlators in terms of the topological susceptibility and the theta dependence. Applying this formula, we show that topological susceptibility can be measured through two-point functions of pseudoscalar operator.
Open AccessTheta vacuum physics from QCD at fixed topology
We propose a method to obtain physical quantities in the theta vacuum from those at fixed topology, which are different by finite size effects. Extending the work by Brower et al., we derive the formula to estimate these finite size corrections for arbitrary correlators in terms of the topological susceptibility and the theta dependence. Applying this formula, we show that topological susceptibility can be measured through two-point functions of pseudoscalar operator.
- 3 November 2006
- Published by American Physical Society (APS) in Physical Review D
- Vol. 74 (9) , 094505
Lattice gauge action suppressing near-zero modes ofWe propose a lattice action including unphysical Wilson fermions with a negative mass of the order of the inverse lattice spacing. With this action, the exact zero mode of the Hermitian Wilson-Dirac operator cannot appear and near-zero modes are strongly suppressed. By measuring the spectral density , we find a gap near on the configurations generated with the standard and improved gauge actions. This gap provides a necessary condition for the proof of the exponential locality of the overlap-Dirac operator by Hernandez, Jansen, and Lüscher. Since the number of near-zero modes is small, the numerical cost to calculate the matrix sign function of is significantly reduced, and the simulation including dynamical overlap fermions becomes feasible. We also introduce a pair of twisted mass pseudofermions to cancel the unwanted higher mode effects of the Wilson fermions. The gauge coupling renormalization due to the additional fields is then minimized. The topological charge measured through the index of the overlap-Dirac operator is conserved during continuous evolutions of gauge field variables.- 3 November 2006
- Published by American Physical Society (APS) in Physical Review D
- Vol. 74 (9) , 094505
Lattice gauge action suppressing near-zero modes ofWe propose a lattice action including unphysical Wilson fermions with a negative mass of the order of the inverse lattice spacing. With this action, the exact zero mode of the Hermitian Wilson-Dirac operator cannot appear and near-zero modes are strongly suppressed. By measuring the spectral density , we find a gap near on the configurations generated with the standard and improved gauge actions. This gap provides a necessary condition for the proof of the exponential locality of the overlap-Dirac operator by Hernandez, Jansen, and Lüscher. Since the number of near-zero modes is small, the numerical cost to calculate the matrix sign function of is significantly reduced, and the simulation including dynamical overlap fermions becomes feasible. We also introduce a pair of twisted mass pseudofermions to cancel the unwanted higher mode effects of the Wilson fermions. The gauge coupling renormalization due to the additional fields is then minimized. The topological charge measured through the index of the overlap-Dirac operator is conserved during continuous evolutions of gauge field variables.- Open Access
- 14 December 2005
- Published by Sissa Medialab Srl
- Vol. 20, 123
Overlap fermion with topology conserving gauge action
- 14 December 2005
- Published by Sissa Medialab Srl
- Vol. 20, 123
Open AccessOverlap fermion with topology conserving gauge action
- Open Access
Study of 1/m corrections in HQET
We report our exploratory study on the matching condition of HQET with QCD including 1/m corrections. We introduce a new observable from the dependence of the heavy-light effective energy on the twisted boundary condition parameter $\theta$, which could be used to match the kinetic term $\vec{D}^2/(2m)$. Carrying out quenched QCD simulations for fixed lattice spacing in small volumes with O(a)-improved Wilson fermions, we study the 1/m dependence of this observable, from which the static limit and 1/m coefficient can be extracted. We also compare our preliminary result with HQET.Open AccessStudy of 1/m corrections in HQET
We report our exploratory study on the matching condition of HQET with QCD including 1/m corrections. We introduce a new observable from the dependence of the heavy-light effective energy on the twisted boundary condition parameter $\theta$, which could be used to match the kinetic term $\vec{D}^2/(2m)$. Carrying out quenched QCD simulations for fixed lattice spacing in small volumes with O(a)-improved Wilson fermions, we study the 1/m dependence of this observable, from which the static limit and 1/m coefficient can be extracted. We also compare our preliminary result with HQET.