HEP Lattice·hep-lat
16 papers—16 primary·0 cross-listed·reconstructed*
We study the chiral condensate, , and various quark bilinear vertex functions for domain wall fermions at different lattice scales, with both the Wilson and DBW2 gauge actions, in both quenched and dynamical fermion simulations. We use the vertex functions to calculate renormalization factors within a non-perturbative scheme.
T. Hashimoto🇯🇵 · M. Horibe🇯🇵 · A. Hayashi🇯🇵
We develop a systematic description of Weyl and Fano operators on a lattice phase space. Introducing the so-called ghost variable even on an odd lattice, odd and even lattices can be treated in a symmetric way. The Wigner function is defined using these operators on the quantum phase space, which can be interpreted as a spin phase space. If we extend the space with a dichotomic variable, a positive distribution function can be defined on the new space. It is shown that there exits a quantum Markov process on the extended space which describes the time evolution of the distribution function.
CP-PACS · JLQCD Collaboration: T.Kaneko · S.Aoki · M.Fukugita · S.Hashimoto · K-I.Ishikawa · T.Ishikawa · N.Ishizuka · Y.Iwasaki · K.Kanaya · Y.Kuramashi · M.Okawa and 4 other authors
We report on a calculation of the light hadron spectrum and quark masses in three-flavor dynamical QCD using the non-perturbatively O(a)-improved Wilson quark action and a renormalization-group improved gauge action. Simulations are carried out on a 16^3 \times 32 lattice at \beta=1.9, where a^{-1} \simeq 2GeV, with 6 ud quark masses corresponding to m_{pi}/m_{rho} \simeq 0.64-0.77 and 2 s quark masses close to the physical value. We observe that the inclusion of dynamical strange quark brings the lattice QCD meson spectrum to good agreement with experiment. Dynamical strange quarks also lead to a reduction of the uds quark masses by about 15%.
This thesis is concerned with two topics in Hamiltonian lattice gauge theory: improvement and the application of analytic techniques. On the topic of improvement, we develop a direct method for improving lattice Hamiltonians for gluons, in which linear combinations of gauge invariant lattice operators are chosen to cancel the lowest order discretisation errors. On the topic of analytic methods, we extend the techniques that have been used in 2+1 dimensional SU(2) variational calculations for many years, to the general case of SU(N). For this purpose a number of group integrals are calculated in terms of Toeplitz determinants. As generating functions these group integrals allow the calculation of all matrix elements appearing in variational glueball mass calculations in 2+1 dimensions. Making use of these analytic techniques, glueball masses in various symmetry sectors are calculated with N as large as 25 allowing extrapolations to infinite N to be performed. We finish with a feasibility study of applying analytic Hamiltonian techniques in 3+1 dimensional calculations.
CP-PACS · JLQCD Collaborations: N. Tsutsui · S. Aoki · M. Fukugita · S. Hashimoto · K-I. Ishikawa · T. Ishikawa · N. Ishizuka · Y. Iwasaki · K. Kanaya · T. Kaneko · Y. Kuramashi and 5 other authors
We present a lattice QCD calculation of the parameters \alpha and \beta which are necessary in the theoretical estimation of the proton lifetime in grand unified theories (GUTs) using chiral lagrangian approach. The simulation is carried out using the Wilson quark action at three gauge coupling constants in the quenched approximation. We obtain |\alpha(2GeV)|=0.0091(08)(^{+10}_{-19})GeV^3 and |\beta(2GeV)|=0.0098(08)(^{+10}_{-20})GeV^3 in the continuum limit where the first error is statistical and the second one is due to scale setting.
Results at NLO in (PQ)ChPT for extracting from lattice data are discussed.
CP-PACS · JLQCD Collaboration: K-I. Ishikawa · S. Aoki · M. Fukugita · S. Hashimoto · N. Ishizuka · Y. Iwasaki · K. Kanaya · T.Kaneko · Y. Kuramashi · V. Lesk · M. Okawa and 5 other authors
The non-perturbative determined by the Schrödinger functional (SF) method with the RG-improved gauge action in dynamical QCD shows a finite volume effect when the numerical simulations are carried out at a constant lattice size . We remove the unwanted finite volume effect by keeping physical lattice extent at a constant. The details of the method and the result obtained for non-perturbative with a constant are reported.
We discuss the possible form of gluon and ghost propagators in the infrared region of Yang-Mills theory in the covariant gauge from the viewpoint of general principles of quantized gauge field theories.
M. Imachi🇯🇵 · Y. Shinno🇯🇵 · H. Yoneyama🇯🇵
In Monte Carlo simulation, lattice field theory with a term suffers from the sign problem. This problem can be circumvented by Fourier-transforming the topological charge distribution . Although this strategy works well for small lattice volume, effect of errors of becomes serious with increasing volume and prevents one from studying the phase structure. This is called flattening. As an alternative approach, we apply the maximum entropy method (MEM) to the Gaussian . It is found that the flattening could be much improved by use of the MEM.
Y. Nakamura🇯🇵 · V. Bornyakov🇷🇺 · M.N. Chernodub🇷🇺 · Y. Koma🇩🇪 · Y. Mori🇯🇵 · M.I. Polikarpov🇷🇺 · G. Schierholz🇩🇪 · A. Slavnov🇷🇺 · H. Stuben🇩🇪 · T. Suzuki🇯🇵 · P. Uvarov🇷🇺 · A.I. Veselov🇷🇺
We present results for QCD with flavors of dynamical quarks using nonperturbatively improved Wilson fermions at finite temperature on and lattices. We determine the transition temperature in the range of quark masses . After fixing the Maximal Abelian gauge we investigate the contribution of Abelian monopoles to the Polyakov loop, Polyakov loop susceptibility and confirm Abelian and monopole dominance in full QCD.
Luigi Del Debbio🇮🇹 · Claudio Pica🇮🇹
The chiral symmetry at finite lattice spacing of Ginsparg-Wilson fermionic actions constrains the renormalization of the lattice operators; in particular, the topological susceptibility does not require any renormalization, when using a fermionic estimator to define the topological charge. Therefore, the overlap formalism appears as an appealing candidate to study the continuum limit of the topological susceptibility while keeping the systematic errors under theoretical control. We present results for the SU(3) pure gauge theory using the index of the overlap Dirac operator to study the topology of the gauge configurations. The topological charge is obtained from the zero modes of the overlap and using a new algorithm for the spectral flow analysis. A detailed comparison with cooling techniques is presented. Particular care is taken in assessing the systematic errors. Relatively high statistics (500 to 1000 independent configurations) yield an extrapolated continuum limit with errors that are comparable with other methods. Our current value from the overlap is .
Slavo Kratochvila (ETH Zurich)🇨🇭 · Philippe de Forcrand (ETH Zurich & CERN)🇨🇭
While the grand canonical partition function Z_{GC}(mu) with chemical potential mu explicitly breaks the Z_3 symmetry with the Dirac determinant, the canonical partition function at fixed baryon number Z_C(B) is manifestly Z_3-symmetric. We compare Z_{GC}(mu=0) and Z_C(B=0) formally and by numerical simulations, in particular with respect to properties of the deconfinement transition. Differences between the two ensembles, for physical observables characterising the phase transition, vanish with increasing lattice size. We show numerically that the free energy density is the same for both ensembles in the thermodynamic limit.
Michele Caselle🇮🇹 · Martin Hasenbusch🇩🇪 · Marco Panero🇮🇹
The effective string picture of confinement is used to derive theoretical predictions for the interquark potential at finite temperature. At short distances, the leading string correction to the linear confining potential between a heavy quark-antiquark pair is the "Lüscher term''. We assume a Nambu--Goto effective string action, and work out subleading contributions in an analytical way. We discuss the contribution given by a possible ``boundary term'' in the effective action, comparing these predictions with results from simulations of lattice gauge theory in three dimensions, obtained with an algorithm which exploits the duality of the gauge model with the Ising spin model.
We determine the free field hypercubic Dirac operator which is optimally close to satisfying the Ginsparg-Wilson relation. Inserting this operator into the overlap formula, we show that the analytic locality bound on the resulting overlap Dirac operator is substantially stronger than in the standard case. This improvement generally persists in gauge backgrounds when the plaquette variables are all close to unity.
M. Hasenbusch🇩🇪 · K. Jansen🇩🇪 · D. Pleiter🇩🇪 · H. St"uben🇩🇪 · P. Wegner🇩🇪 · T. Wettig🇺🇸 · H. Wittig🇩🇪
We define a benchmark suite for lattice QCD and report on benchmark results from several computer platforms. The platforms considered are apeNEXT, CRAY T3E, Hitachi SR8000, IBM p690, PC-Clusters, and QCDOC.
V. Gimenez🇪🇸 · L. Giusti🇨🇭 · S. Guerriero🇮🇹 · V. Lubicz🇮🇹 · G. Martinelli🇮🇹 · S. Petrarca🇮🇹 · J. Reyes🇮🇹 · B. Taglienti🇮🇹 · E. Trevigne🇮🇹
We present an exploratory study of a gauge-invariant non-perturbative renormalization technique. The renormalization conditions are imposed on correlation functions of composite operators in coordinate space on the lattice. Numerical results for bilinears obtained with overlap and O(a)-improved Wilson fermions are presented. The measurement of the quark condensate is also discussed.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.