HEP Lattice·hep-lat

Wed·Sep 4, 2002Wednesday·September 4, 2002

30 papers—28 primary·2 cross-listed·reconstructed*

01*
Unquenched Numerical Stochastic Perturbation Theory
F. Di Renzo🇮🇹 · V. Miccio (Parma U.)🇮🇹 · L. Scorzato (DESY)🇩🇪
The inclusion of fermionic loops contribution in Numerical Stochastic Perturbation Theory (NSPT) has a nice feature: it does not cost so much (provided only that an FFT can be implemented in a fairly efficient way). Focusing on Lattice SU(3), we report on the performance of the current implementation of the algorithm and the status of first computations undertaken.
hep-latNucl.Phys.B Proc.Suppl.(2003)·5 citations
02*
New algorithm of the high-temperature expansion for the Ising model in three dimensions
H. Arisue🇯🇵 · T. Fujiwara🇯🇵
New algorithm of the finite lattice method is presented to generate the high-temperature expansion series of the Ising model. It enables us to obtain much longer series in three dimensions when compared not only to the previous algorithm of the finite lattice method but also to the standard graphical method. It is applied to extend the high-temperature series of the simple cubic Ising model from beta^{26} to beta^{46} for the free energy and from beta^{25} to beta^{32} for the magnetic susceptibility.
hep-latNucl.Phys.B Proc.Suppl.(2003)·3 citations
03*
$K^{+} \to π^{+} π^{0}$ decays at next-to-leading order in the chiral expansion on finite volumes
C.-J.D. Lin (Southampton)🇬🇧 · G. Martinelli (Rome1)🇮🇹 · E. Pallante (SISSA)🇮🇹 · C.T. Sachrajda (Southampton and CERN)🇬🇧 · G. Villadoro (Rome1)🇮🇹
We present the ingredients for determining $K^{+} \to π^{+} π^{0}$ matrix elements via the combination of lattice QCD and chiral perturbation theory ( $χ$ PT). By simulating these matrix elements at unphysical kinematics, it is possible to determine all the low-energy constants (LECs) for constructing the physical $K^{+} \to π^{+} π^{0}$ amplitudes at next-to-leading order (NLO) in the chiral expansion. In this work, the one-loop chiral corrections are calculated for arbitrary meson four-momenta, in both $χ$ PT and quenched $χ$ PT (q $χ$ PT), and the finite-volume effects are studied.
hep-lathep-phNucl.Phys.B Proc.Suppl.(2003)·5 citations
04*
Simulating non-commutative field theory
W. Bietenholz🇩🇪 · F. Hofheinz🇩🇪 · J. Nishimura🇯🇵
Non-commutative (NC) field theories can be mapped onto twisted matrix models. This mapping enables their Monte Carlo simulation, where the large N limit of the matrix models describes the continuum limit of NC field theory. First we present numeric results for 2d NC gauge theory of rank 1, which turns out to be renormalizable. The area law for the Wilson loop holds at small area, but at large area we observe a rotating phase, which corresponds to an Aharonov-Bohm effect. Next we investigate the NC phi^4 model in d=3 and explore its phase diagram. Our results agree with a conjecture by Gubser and Sondhi in d=4, who predicted that the ordered regime splits into a uniform phase and a phase dominated by stripe patterns.
hep-lathep-thNucl.Phys.B Proc.Suppl.(2003)·40 citations
05*
The Upsilon Spectrum from Lattice QCD with 2+1 Flavors of Dynamical Quarks
A. Gray🇬🇧 · C. Davies🇬🇧 · M. Alford🇬🇧 · E. Follana🇬🇧 · J. Hein🇬🇧 · G. P. Lepage🇺🇸 · Q. Mason🇺🇸 · M. Nobes🇨🇦 · J. Shigemitsu🇺🇸 · H. Trottier🇨🇦 · M. Wingate🇺🇸
We describe the bottomonium spectrum obtained on the MILC configurations which incorporate 2+1 flavors of dynamical quarks. We compare to quenched and 2 flavor results also on MILC configurations. We show that the lattice spacing determination using different quantities shows clear signs of convergence with 2+1 flavors and give results for the leptonic width and hyperfine splitting, in the form of the ratio of the 1st excited state of the Upsilon to that of the ground state.
hep-latNucl.Phys.B Proc.Suppl.(2003)·20 citations
06*
Recent results on the running coupling in QCD with two massless flavours
M. Della Morte🇩🇪 · R. Frezzotti🇮🇹 · J. Heitger🇩🇪 · F. Knechtli🇩🇪 · J. Rolf🇩🇪 · R. Sommer🇩🇪 · U. Wolff🇩🇪
We report on the latest results on the running coupling of two flavour QCD in the Schrödinger functional scheme. Results for the step scaling function are obtained from simulations on lattices $L / a = 8$ and $L / a = 16$ which confirm the first results from lattices $L / a = 4, 5, 6$ presented one year ago by the ALPHA collaboration. We also discuss some algorithmic aspects, in particular concerning the occurrence of metastable states. A modified sampling, in order to estimate the proper weight of these states in the path integral, is proposed and tested.
hep-latNucl.Phys.B Proc.Suppl.(2003)·20 citations
07*
Chiral Nonanalytic Behaviour: The Edinburgh Plot
Stewart V. Wright🇬🇧 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺
The Edinburgh Plot is a scale independent way of presenting lattice QCD calculations over a wide range of quark masses. In this sense it is appealing as an indicator of how the approach to physical quark masses is progressing. The difficulty remains that even the most state of the art calculations are still at quark masses that are too heavy to apply dimensionally-regulated chiral perturbation theory. We present a method allowing predictions of the behaviour of the Edinburgh plot, in both the continuum, and on the lattice.
hep-latNucl.Phys.B Proc.Suppl.(2003)·2 citations
08*
Running quark mass in two flavor QCD
F. Knechtli🇩🇪 · M. Della Morte🇩🇪 · J. Rolf🇩🇪 · R. Sommer🇩🇪 · I. Wetzorke🇩🇪 · U. Wolff (ALPHA collaboration)🇩🇪
We present first results for the step scaling function sigma_P of the renormalization factor Z_P of the pseudoscalar density. The simulations are performed within the framework of the Schroedinger functional with two flavors of O(a) improved Wilson fermions. The knowledge of sigma_P is required to compute the renormalization group invariant quark masses. We also study the performance of a variant of the HMC algorithm using two pseudofermion fields.
hep-latNucl.Phys.B Proc.Suppl.(2003)·18 citations
09*
Dynamical fermions on anisotropic lattices
CP-PACS Collaboration : T.Umeda🇯🇵 · S.Aoki🇯🇵 · M.Fukugita🇯🇵 · K-I.Ishikawa🇯🇵 · N.Ishizuka🇯🇵 · Y.Iwasaki🇯🇵 · K.Kanaya🇯🇵 · Y.Kuramashi🇯🇵 · V.Lesk🇯🇵 · Y.Namekawa🇯🇵 · M.Okawa🇯🇵 · Y.Taniguchi🇯🇵 · A.Ukawa🇯🇵 · T.Yoshie🇯🇵
We report on our study of two-flavor full QCD on anisotropic lattices using $O (a)$ -improved Wilson quarks coupled with an RG-improved glue. The bare gauge and quark anisotropies corresponding to the renormalized anisotropy $ξ = a_{s} / a_{t} = 2$ are determined as functions of $β$ and $κ$ , using the Wilson loop and the meson dispersion relation at several lattice cutoffs and quark masses.
hep-latNucl.Phys.B Proc.Suppl.(2003)·0 citations
10*
The phase diagram of the three-dimensional Z2 gauge Higgs system at zero and finite temperature
Luigi Genovese🇮🇹 · Ferdinando Gliozzi🇮🇹 · Antonio Rago🇮🇹 · Christian Torrero🇮🇹
We study the effect of adding a matter field to the Z2 gauge model in three dimensions at zero and finite temperature. Up to a given value of the parameter regulating the coupling, the matter field produces a slight shift of the transition line without changing the universality class of the pure gauge theory, as seen by finite size scaling analysis or by comparison, in the finite temperature case, to exact formulas of conformal field theory. At zero temperature the critical line turns into a first-order transition. The fate of this kind of transition in the finite temperature case is discussed.
hep-latNucl.Phys.B Proc.Suppl.(2003)·15 citations
11*
On the Continuum Limit of the Discrete Regge Model in 4d
Elmar Bittner🇦🇹 · Wolfhard Janke🇩🇪 · Harald Markum🇦🇹
The Regge Calculus approximates a continuous manifold by a simplicial lattice, keeping the connectivities of the underlying lattice fixed and taking the edge lengths as degrees of freedom. The Discrete Regge model employed in this work limits the choice of the link lengths to a finite number. This makes the computational evaluation of the path integral much faster. A main concern in lattice field theories is the existence of a continuum limit which requires the existence of a continuous phase transition. The recently conjectured second-order transition of the four-dimensional Regge skeleton at negative gravity coupling could be such a candidate. We examine this regime with Monte Carlo simulations and critically discuss its behavior.
hep-latNucl.Phys.B Proc.Suppl.(2003)·2 citations
12*
Confining string and P-vortices in the indirect Z(2) projection of SU(2) lattice gauge theory
V. G. Bornyakov🇷🇺 · A. V. Kovalenko🇷🇺 · M. I. Polikarpov🇷🇺 · D. A. Sigaev🇷🇺
We study the distribution of P-vortices near the confining string in the indirect Z(2) projection of SU(2) lattice gauge theory. It occurs that the density of vortices is constant at large distances and strongly suppressed near the line connecting the test quark-antiquark pair. This means that the condensate of P-vortices is broken inside the confining string. We also find that the width of the P-vortex density distribution is proportional to the logarithm of the distance between the quark and antiquark.
hep-latNucl.Phys.B Proc.Suppl.(2003)·7 citations
13*
Vacuum Structure of the Ichimatsu-Decomposed Lattice Models
K. Itoh (Niigata Univ.)🇯🇵 · M. Kato (Inst. of Physics, Univ. of Tokyo)🇯🇵 · M. Murata (Niigata Univ.)🇯🇵 · H. Sawanaka (Niigata Univ.)🇯🇵 · H. So (Niigata Univ.)🇯🇵
We proposed an `Ichimatsu'-decomposed lattice gauge theory with fermionic symmetries. The vacuum structures of the gauge sector with two coupling constants ( $β_{p}, β_{c}$ ) are investigated for 3-dimensional Z $_{2}$ and 4-dimensional SU(2) cases using mean-field approximation and numerical simulation. We found two phases on the ( $β_{p}, β_{c}$ ) phase diagram for 3-dim. Z $_{2}$ case, while the diagram is a single phase for the latter.
hep-latNucl.Phys.B Proc.Suppl.(2003)·2 citations
14*
Gluon propagators in maximal abelian gauge of SU(2) lattice gauge theory
V. G. Bornyakov🇷🇺 · S. M. Morozov🇷🇺 · M. I. Polikarpov🇷🇺
We study propagators of diagonal and off-diagonal gluons in the momentum space in maximal abelian gauge of SU(2) lattice gauge theory. Remaining U(1) degrees of freedom are fixed using Landau gauge. We find substantial difference between the propagator of the diagonal and the off-diagonal gluon in the infrared region. The propagator of the off-diagonal gluon is suppressed in comparison with that of the diagonal gluon at small momenta. In the ultraviolet region both propagators behave as in nonabelian Landau gauge.
hep-latNucl.Phys.B Proc.Suppl.(2003)·5 citations
15*
Non-commutative Solitons in Finite Quantum Mechanics
E. G. Floratos🇬🇷 · S. Nicolis🇫🇷
We construct the unitary evolution operators that realize the quantization of linear maps of SL(2,R) over phase spaces of arbitrary integer discretization N and show the non-trivial dependence on the arithmetic nature of N. We discuss the corresponding uncertainty principle and construct the corresponding coherent states, that may be interpreted as non-commutative solitons.
hep-latNucl.Phys.B Proc.Suppl.(2003)·2 citations
16*
Transport coefficients from the lattice?
Gert Aarts🇺🇸 · Jose M. Martinez Resco (Ohio State)🇺🇸
The prospects of extracting transport coefficients from euclidean lattice simulations are discussed. Some general comments on the reconstruction of spectral functions using the Maximal Entropy Method are given as well.
hep-lathep-phnucl-thNucl.Phys.B Proc.Suppl.(2003)·28 citations
17*
Fermionic Symmetry in Ichimatsu-Decomposed Lattice Models
K. Itoh🇯🇵 · M. Kato🇯🇵 · H. Sawanaka🇯🇵 · H. So🇯🇵 · N. Ukita🇯🇵
We present the lattice models with exact fermionic symmetries relating fermions and link variables. The plaquettes are distributed in an Ichimatsu pattern (chequered). We explain this peculiar structure allows us to have a translation in the algebra of the fermionic symmetries.
hep-latNucl.Phys.B Proc.Suppl.(2003)·2 citations
18*
Comparing the R algorithm and RHMC for staggered fermions
M. A. Clark🇬🇧 · B. Joo🇬🇧 · A. D. Kennedy🇬🇧
The R algorithm is widely used for simulating two flavours of dynamical staggered fermions. We give a simple proof that the algorithm converges to the desired probability distribution to within O(dt^2) errors, but show that the relevant expansion parameter is (dt/m)^2, m being the quark mass. The Rational Hybrid Monte Carlo (RHMC) algorithm provides an exact (i.e., has no step size errors) alternative for simulating the square root of the staggered Dirac operator. We propose using it to test the validity of the R algorithm for simulations carried out with dt m.
hep-latNucl.Phys.B Proc.Suppl.(2003)·17 citations
19*
Light quark masses from UKQCD's dynamical simulations with O(a)-improved Wilson fermions
D.J.Hepburn · UKQCD Collaboration
I present preliminary results on the light quark masses from a partially quenched analysis of UKQCD's dynamical datasets.
hep-latNucl.Phys.B Proc.Suppl.(2003)·5 citations
20*
Multiple molecular dynamics time-scales in Hybrid Monte Carlo fermion simulations
Mike Peardon🇮🇪 · James Sexton (for the TrinLat Collaboration)🇮🇪
A scheme for separating the high- and low-frequency molecular dynamics modes in Hybrid Monte Carlo (HMC) simulations of gauge theories with dynamical fermions is presented. The algorithm is tested in the Schwinger model with Wilson fermions.
hep-latNucl.Phys.B Proc.Suppl.(2003)·30 citations
21*
Lattice QCD with light dynamical quarks
F. Farchioni (Munster U., ITP)🇩🇪 · C. Gebert🇩🇪 · I. Montvay🇩🇪 · L. Scorzato (DESY)🇩🇪
We report on the simulation of QCD with light dynamical quarks using the two-step multi-boson (TSMB) algorithm. In an exploratory study with two flavours of quarks at lattice spacing about 0.27 fm and with quark mass down to one sixth of the strange quark mass eigenvalue spectra and autocorrelations have been studied. Here we present results on the volume dependence as well as tests of possible algorithmic improvements.
hep-latNucl.Phys.B Proc.Suppl.(2003)·4 citations
22*
Lyapunov exponents in Minkowskian U(1) gauge theory
Harald Markum🇦🇹 · Rainer Pullirsch🇦🇹 · Wolfgang Sakuler🇦🇹
U(1) gauge fields are decomposed into a monopole and photon part across the phase transition from the confinement to the Coulomb phase. We analyze the leading Lyapunov exponents of such gauge field configurations on the lattice which are initialized by quantum Monte Carlo simulations. We observe that the monopole field carries the same Lyapunov exponent as the original U(1) field. Evidence is found that monopole fields stay chaotic in the continuum whereas the photon fields are regular.
hep-latNucl.Phys.B Proc.Suppl.(2003)·5 citations
23*
Running coupling constant and propagators in SU(2) Landau gauge
Jacques C. R. Bloch🇩🇪 · Attilio Cucchieri🇧🇷 · Kurt Langfeld🇩🇪 · Tereza Mendes🇧🇷
We present a numerical study of the running coupling constant and of the gluon and ghost propagators in minimal Landau gauge. Simulations are done in pure SU(2) lattice gauge theory for several values of beta and lattice sizes. We use two different lattice setups.
hep-latNucl.Phys.B Proc.Suppl.(2003)·42 citations
24*
Composite reweighting with Imaginary Chemical Potentials in SU(3)
P.R. Crompton🇩🇪
We review the overlap pathology of the Glasgow reweighting method for finite density QCD, and discuss the sampling bias that effects the determination of the ensemble-averaged fugacity polynomial expansion coefficients that form the Grand Canonical Partition function. The expectation of the difference in free energies between canonical partition functions generated with different measures is presented as an indicator of a systematic quark number dependent biasing in the reweighting approach. The advantages of building up an unbiased polynomial expansion for the Grand Canonical Partition function through a series of parallel ensembles generated by reweighting with imaginary chemical potentials are then contrasted with addressing the overlap pathology through a secondary reweighting.
hep-latNucl.Phys.B Proc.Suppl.(2003)·6 citations
25*
The Paraldor Project
T. Ashby🇬🇧 · D. Galletly🇬🇧 · B. Joo🇬🇧 · A. D. Kennedy🇬🇧 · G. Lacagnina🇬🇧
Paraldor is an experiment in bringing the power of categorical languages to lattice QCD computations. Our target language is Aldor, which allows the capture of the mathematical structure of physics directly in the structure of the code using the concepts of categories, domains and their inter-relationships in a way which is not otherwise possible with current popular languages such as Fortran, C, C++ or Java. By writing high level physics code portably in Aldor, and implementing switchable machine dependent high performance back-ends in C or assembler, we gain all the power of categorical languages such as modularity, portability, readability and efficiency.
hep-latNucl.Phys.B Proc.Suppl.(2003)·0 citations
26*
Electric Polarizability of Hadrons
Joe Christensen🇺🇸 · Frank X. Lee🇺🇸 · Walter Wilcox🇺🇸 · Leming Zhou🇺🇸
The electric polarizability of a hadron allows an external electric field to shift the hadron mass. We try to calculate the electric polarizability for several hadrons from their quadratic response to the field at a=0.17fm using an improved gauge field and the clover quark action. Results are compared to experiment where available.
hep-latNucl.Phys.B Proc.Suppl.(2003)·12 citations
27*
Residual mass effects in improved domain wall fermions
Pilar Hernández🇨🇭 · Karl Jansen🇩🇪 · Kei-ichi Nagai🇨🇭
In order to improve simulations with domain wall fermions (DWFs), it has been suggested to project out a number of low-lying eigenvalues of the 4-dimensional Dirac operator that generates the transfer matrix of DWF. We investigate how this projection method affects chiral properties of quenched DWF. In particular, we study the behaviour of the residual mass as a function of the size of the extra dimension.
hep-latNucl.Phys.B Proc.Suppl.(2003)·1 citation
28*
Twisted mass QCD and the $Δ I = 1/2$ rule
C. Pena🇮🇹 · S. Sint🇨🇭 · A. Vladikas🇮🇹
We show that the application of twisted mass QCD (tmQCD) with four (Wilson) quark flavours to the computation of lattice weak matrix elements relevant to $Δ I = 1/2$ transitions has important advantages: the renormalisation of $K \to π$ matrix elements does not require the subtraction of other dimension six operators, the divergence arising from the subtraction of lower dimensional operators is softened by one power of the lattice spacing and quenched simulations do not suffer from exceptional configurations at small pion mass. This last feature is also retained in the tmQCD computation of $K \to π π$ matrix elements, which, as far as renormalisation and power subtractions are concerned, has properties analogous to the standard Wilson case.
hep-latNucl.Phys.B Proc.Suppl.(2003)·12 citations
29*
Hadron correlators, spectral functions and thermal dilepton rates from lattice QCD
F. Karsch🇩🇪 · S. Datta🇩🇪 · E. Laermann🇩🇪 · P. Petreczky🇩🇪 · S. Stickan🇩🇪 · I. Wetzorke🇩🇪
We discuss information on thermal modifications of hadron properties which can be extracted from the structure of Euclidean correlation functions of hadronic currents as well as more direct information obtained through the reconstruction of the spectral functions based on the Maximum Entropy Method.
↳ hep-phhep-latnucl-thNPA(2003)·81 citations
30*
An Instanton Picture O.P.E. <A^2> Condensate?
Ph. Boucaud🇫🇷 · F. De Soto🇪🇸 · A. Donini🇮🇹 · J.P. Leroy🇫🇷 · A. Le Yaouanc🇫🇷 · J. Micheli🇫🇷 · H. Moutarde🇫🇷 · O. Pène🇫🇷 · J. Rodríguez-Quintero🇪🇸
Gluon two- and three-point Green Functions computed in Landau gauge from the lattice show the existence of power corrections to the purely perturbative expressions, that can be explained through an Operator Product Expansion as the influence of a non gauge invariant mass dimension two condensate. The relationship of this condensate with topological properties of QCD, namely instantons, will be studied, giving a first estimate of the contribution of instantons to this condensate based in the direct lattice measure, after a cooling process, of the instanton liquid properties.
↳ hep-phhep-latNucl.Phys.B Proc.Suppl.(2003)·5 citations

* 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.