Sinya Aoki

Abstract We review lattice results related to pion, kaon, D -meson, B -meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor $$f_+(0)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>f</mml:mi><mml:mo>+</mml:mo></mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mn>0</mml:mn><mml:mo>)</mml:mo></mml:mrow></mm

We present the first results of the PACS-CS project which aims to simulate $2+1$ flavor lattice QCD on the physical point with the nonperturbatively $O(a)$-improved Wilson quark action and the Iwasaki gauge action. Numerical simulations are carried out at $\ensuremath{\beta}=1.9$, corresponding to the lattice spacing of $a=0.0907(13)\text{ }\text{ }\mathrm{fm}$, on a ${32}^{3}\ifmmode\times\else\texttimes\fi{}64$ lattice with the use of the domain-decomposed HMC algorithm to reduce the up-down q

Based on analysis of the lattice Gross-Neveu model we propose a new phase structure for lattice QCD in the presence of Wilson fermions. A new method for improving the scaling behavior of the chiral order parameter is also proposed.

We present results of a large-scale simulation for the flavor nonsinglet light hadron spectrum in quenched lattice QCD with the Wilson quark action. Hadron masses are calculated at four values of lattice spacing in the range a approximately 0.1-0.05 fm on lattices with a physical extent of 3 fm at five quark masses corresponding to m(pi)/m(rho) approximately 0.75-0.4. The calculated spectrum in the continuum limit shows a systematic deviation from experiment, though the magnitude of deviation is

We present a lattice QCD calculation of the $\ensuremath{\rho}$ meson decay width via the $P$-wave scattering phase shift for the $I=1$ two-pion system. Our calculation uses full QCD gauge configurations for ${N}_{f}=2$ flavors generated using a renormalization group improved gauge action and an improved Wilson fermion action on a ${12}^{3}\ifmmode\times\else\texttimes\fi{}24$ lattice at ${m}_{\ensuremath{\pi}}/{m}_{\ensuremath{\rho}}=0.41$ and the lattice spacing $1/a=0.92\text{ }\text{ }\mathr

We present the results of the physical point simulation in $2+1$ flavor lattice QCD with the nonperturbatively $O(a)$-improved Wilson quark action and the Iwasaki gauge action at $\ensuremath{\beta}=1.9$ on a ${32}^{3}\ifmmode\times\else\texttimes\fi{}64$ lattice. The physical quark masses together with the lattice spacing is determined with ${m}_{\ensuremath{\pi}}$, ${m}_{K}$ and ${m}_{\ensuremath{\Omega}}$ as physical inputs. There are two key algorithmic ingredients to make possible the direc

In finite volume the partition function of QCD with a given $\ensuremath{\theta}$ 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

We present a high statistics study of the light hadron spectrum and quark masses in QCD with two flavors of dynamical quarks. Numerical simulations are carried out using the plaquette gauge action and the O(a)-improved Wilson quark action at $\ensuremath{\beta}=5.2,$ where the lattice spacing is found to be $a=0.0887(11)\mathrm{fm}$ from the $\ensuremath{\rho}$ meson mass, on a ${20}^{3}\ifmmode\times\else\texttimes\fi{}48$ lattice. At each of five sea quark masses corresponding to ${m}_{\mathrm

We perform a lattice QCD study of the $\ensuremath{\rho}$ meson decay from the ${N}_{f}=2+1$ full QCD configurations generated with a renormalization group improved gauge action and a nonperturbatively $O(a)$-improved Wilson fermion action. The resonance parameters, the effective $\ensuremath{\rho}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}$ coupling constant and the resonance mass, are estimated from the $P$-wave scattering phase shift for the isospin $I=1$ two-pion system. The fin

We reconsider constraints on the eigenvalue density of the Dirac operator in the chiral-symmetric phase of two-flavor QCD at finite temperature. To avoid possible ultraviolet divergences, we work on a lattice, employing the overlap Dirac operator, which ensures the exact ``chiral'' symmetry at finite lattice spacings. Studying multipoint correlation functions in various channels and taking their thermodynamical limit (and then taking the chiral limit), we obtain stronger constraints than those f

A new resolution to the U(1) problem is proposed without direct reference to spontaneous chiral-symmetry breaking. The parity and flavor symmetry which correspond to the neutral-pion operator are spontaneously broken when we change the mass parameter M. Therefore the neutral pion becomes massless at the phase-transition point where the correlation length diverges, while the \ensuremath{\eta} meson remains massive. Furthermore, the charged pion becomes the Nambu-Goldstone boson in the parity- and

Lattice QCD should allow quantitative predictions for the heavy quark physics from first principles. Up to now, however, most approaches have based on the nonrelativistic effective theory, with which the continuum limit cannot be taken. In this paper we investigate feasibility of relativistic approaches to the heavy quark physics in lattice QCD. We first examine validity of the idea that the use of the anisotropic lattice could be advantageous to control the mQa corrections. Our perturbative cal

We present a model-independent calculation of hadron matrix elements for all dimension-6 operators associated with baryon number violating processes using lattice QCD. The calculation is performed with the Wilson quark action in the quenched approximation at $\ensuremath{\beta}{=6/g}^{2}=6.0$ on a ${28}^{2}\ifmmode\times\else\texttimes\fi{}48\ifmmode\times\else\texttimes\fi{}80$ lattice. Our results cover all the matrix elements required to estimate the partial lifetimes of (proton,neutron)$\ens

We present the details of simulations for the light hadron spectrum in quenched QCD carried out on the CP-PACS parallel computer. Simulations are made with the Wilson quark action and the plaquette gauge action on lattices of size ${32}^{3}\ifmmode\times\else\texttimes\fi{}56--{64}^{3}\ifmmode\times\else\texttimes\fi{}112$ at four values of lattice spacings in the range $a\ensuremath{\approx}0.1--0.05\mathrm{fm}$ and spatial extent ${L}_{s}a\ensuremath{\approx}3\mathrm{fm}.$ Hadronic observables

We calculate the two-pion wave function in the ground state of the $I=2$ $S$-wave system and find the interaction range between two pions, which allows us to examine the validity of the necessary condition for the finite-volume method for the scattering length proposed by L\"uscher. We work in the quenched approximation employing a renormalization group improved gauge action for gluons and an improved Wilson action for quarks at $1/a=1.207(12)\text{ }\mathrm{GeV}$ on ${16}^{3}\ifmmode\times\else