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The Standard Model and the Lattice: The $SU(3)\otimes SU(2) \otimes U(1)$ standard model maps smoothly onto a conventional lattice gauge formulation, including the parity violation of the weak interactions. The formulation makes use of the pseudo-reality of the weak group and requires the inclusion a full generation of...
hep-lat
Reducing cutoff effects in maximally twisted lattice QCD close to the chiral limit: When analyzed in terms of the Symanzik expansion, lattice correlators of multi-local (gauge-invariant) operators with non-trivial continuum limit exhibit in maximally twisted lattice QCD ``infrared divergent'' cutoff effects of the ty...
hep-lat
The Phase Diagram of 2 flavour QCD with improved Actions: It has been proposed, that the chiral continuum limit of 2-flavour QCD with Wilson fermions is brought about by a phase in which flavour and parity symmetry are broken spontaneously at finite lattice spacing. At finite temperature this phase should retract from ...
hep-lat
Renormalization of the effective theory for heavy quarks at small velocity: The slope of the Isgur-Wise function at the normalization point, $\xi^{(1)}(1)$,is one of the basic parameters for the extraction of the $CKM$ matrix element $V_{cb}$ from exclusive semileptonic decay data. A method for measuring this paramet...
hep-lat
A new framework to tune an improved relativistic heavy-quark action: We introduce a new non-perturbative method to tune the parameters of the Columbia formulation of an anisotropic, clover-improved relativistic heavy-quark (RHQ) action. By making use of suitable observables which can be computed at a sequence of heavy-...
hep-lat
Update on onium masses with three flavors of dynamical quarks: We update results presented at Lattice 2005 on charmonium masses. New ensembles of gauge configurations with 2+1 flavors of improved staggered quarks have been analyzed. Statistics have been increased for other ensembles. New results are also available for ...
hep-lat
Chiral logs in twisted mass lattice QCD with large isospin breaking: The pion masses and the pion decay constant are calculated to 1-loop order in twisted mass Wilson chiral perturbation theory, assuming a large pion mass splitting and tuning to maximal twist. Taking the large mass splitting at leading order in the chi...
hep-lat
Improving center vortex detection by usage of center regions as guidance for the direct maximal center gauge: The center vortex model of quantum chromodynamic states that vortices, closed color-magnetic flux, percolate the vacuum. Vortices are seen as the relevant excitations of the vacuum, causing confinement and dy...
hep-lat
Quenched charmonium near the continuum limit: We study relativistic charmonium on very fine quenched lattices (beta=6.4 and 6.6). We concentrate on the calculation of the hyperfine splitting between eta_c and J/psi, aiming for a controlled continuum extrapolation of this quantity. Results for the eta_c and J/psi wave f...
hep-lat
Non-Gaussian fixed point in four-dimensional pure compact U(1) gauge theory on the lattice: The line of phase transitions, separating the confinement and the Coulomb phases in the four-dimensional pure compact U(1) gauge theory with extended Wilson action, is reconsidered. We present new numerical evidence that a par...
hep-lat
Particle Projection Using a Complex Langevin Method: Using complex stochastic quantization, we implement a particle-number projection technique on the partition function of spin-1/2 fermions at finite temperature on the lattice. We discuss the method, its application towards obtaining the thermal properties of finite F...
hep-lat
Chiral phase transition in a random matrix model with three flavors: The chiral phase transition in the conventional random matrix model is the second order in the chiral limit, irrespective of the number of flavors N_f, because it lacks the U_A(1)-breaking determinant interaction term. Furthermore, it predicts an unph...
hep-lat
$B_s$-$\bar{B_s}$ mixing from lattice QCD: We study the $B^0_s-\bar{B^0_s}$ mixing amplitude in Standard Model by computing the relevant hadronic matrix element in the static limit of lattice HQET with the Neuberger light quark action. In the quenched approximation, and after matching to the $\bar{\rm MS}$ scheme in QC...
hep-lat
Domain wall fermion zero modes on classical topological backgrounds: The domain wall approach to lattice fermions employs an additional dimension, in which gauge fields are merely replicated, to separate the chiral components of a Dirac fermion. It is known that in the limit of infinite separation in this new dimension...
hep-lat
Exploring the Spectrum of QCD using the Lattice: The calculation of the spectrum of QCD is key to an understanding of the strong interactions, and vital if we are to capitalize on the experimental study of the spectrum. In this paper, we describe progress towards understanding the spectrum of resonances of both mesons ...
hep-lat
Locality of staggered overlap operators: We give an explicit proof for the locality of staggered overlap operators. The proof covers the original two flavor construction by Adams as well as a single flavor version. As in the case of Neuberger's operator, an admissibility condition for the gauge fields is required.
hep-lat
Gradient flow step-scaling function for SU(3) with ten fundamental flavors: We calculate the step scaling function, the lattice analog of the renormalization group $\beta$-function, for an SU(3) gauge theory with ten fundamental flavors. We present a detailed analysis including the study of systematic effects of our ...
hep-lat
High-degree Polynomial Noise Subtraction: In lattice QCD, the calculation of physical quantities from disconnected quark loop calculations have large variance due to the use of Monte Carlo methods for the estimation of the trace of the inverse lattice Dirac operator. In this work, we build upon our POLY and HFPOLY vari...
hep-lat
Critical Behaviour in the Single Flavor Thirring Model in 2+1d: Results of a lattice field theory simulation of the single-flavor Thirring model in 2+1 spacetime dimensions are presented. The lattice model is formulated using domain wall fermions as a means to recover the correct U(2) symmetries of the continuum model ...
hep-lat
SU(3) Deconfinement in (2+1)d from Twisted Boundary Conditions and Self-Duality: We study the pure SU(3) gauge theory in 2+1 dimensions on the lattice using 't Hooft's twisted boundary conditions to force non-vanishing center flux through the finite volume. In this way we measure the free energy of spacelike center v...
hep-lat
Delta expansion and Wilson fermion in the Gross-Neveu model: Compatibility with linear divergence and continuum limit from inverse-mass expansion: We apply the $\delta$-expansion to the Gross-Neveu model in the large $N$ limit with Wilson fermion and investigate dynamical mass generation from inverse-mass expansion...
hep-lat
(2+1)-flavor QCD Thermodynamics from the Gradient Flow: Recently, we proposed a novel method to define and calculate the energy-momentum tensor (EMT) in lattice gauge theory on the basis of the Yang-Mills gradient flow [1]. In this proceedings, we summarize the basic idea and technical steps to obtain the bulk thermody...
hep-lat
Twist-3 partonic distributions from lattice QCD: Twist-3 partonic distributions contain important information that characterizes nucleon's structure. In this work, we show our lattice exploration of the twist-3 PDFs $g_T(x)$, and $h_L(x)$. We also present our preliminary results on the twist-3 GPD $\tilde{G}_2(x)$. We ...
hep-lat
Light meson masses and decay constants in 2+1 flavour domain wall QCD: We present results for light meson masses and psedoscalar meson decay constants in 2+1 flavour domain wall QCD with the DBW2 and Iwasaki gauge actions, using lattices with linear sizes in the range 1.6 to 2.2fm and $u$ and $d$ quark masses as low as...
hep-lat
Hopping Parameter Expansion for Heavy-Light Systems: We present a technique which permits the calculation of two-point functions of operators containing one heavy quark and an arbitrary number of light quarks as analytic functions of the heavy-quark mass. It is based on the standard Jacobi linear solver used for the ca...
hep-lat
Can Sigma Models Describe Finite Temperature Chiral Transitions?: Large-N expansions and computer simulations indicate that the universality class of the finite temperature chiral symmetry restoration transition in the 3D Gross-Neveu model is mean field theory. This is a counterexample to the standard 'sigma model' sce...
hep-lat
The non-perturbative part of the plaquette in quenched QCD: We define the non-perturbative part of a quantity as the difference between its numerical value and the perturbative series truncated by dropping the order of minimal contribution and the higher orders. For the anharmonic oscillator, the double-well potential ...
hep-lat
Study of SU(2) gauge theories with multiple Higgs fields in different representations: We study two different SU(2) gauge-scalar theories in 3 and 4 spacetime dimensions. Firstly, we focus on the 3 dimensional SU(2) theory with multiple Higgs fields in the adjoint representation, that can be mapped to cuprate systems...
hep-lat
A strategy to study the role of the charm quark in explaining the Delta{I}=1/2 rule: We present a strategy designed to separate several possible origins of the well-known enhancement of the Delta{I}=1/2 amplitude in non-leptonic kaon decays. In particular, we seek to disentangle the contribution of physics at the typ...
hep-lat
$ Δ$ baryon spectroscopy in lattice QCD: A variational analysis is performed within the framework of lattice QCD to extract the masses of the spin-3/2 positive parity $ \Delta^+ $ baryons, including radial excitations. $2+1$ flavour dynamical gauge-field configurations provided by the PACS-CS collaboration via the ILDG...
hep-lat
Review on Composite Higgs Models: Composite Higgs Models explore the possibility that the Higgs boson is an excitation of a new strongly interacting sector giving rise to electro-weak symmetry breaking. After describing how this new sector can be embedded into the Standard Model of elementary particle physics meeting e...
hep-lat
Neural multigrid for gauge theories and other disordered systems: We present evidence that multigrid works for wave equations in disordered systems, e.g. in the presence of gauge fields, no matter how strong the disorder, but one needs to introduce a "neural computations" point of view into large scale simulations: Fir...
hep-lat
New lattice approaches to the $ΔI=1/2$ rule: Lattice QCD should allow a derivation of the $\Delta I=1/2$ rule from first principles, but numerical calculations to date have been plagued by a variety of problems. After a brief review of these problems, we present several new methods for calculating $K\to\pi\pi$ amplitud...
hep-lat
Quark-gluon vertex with an off-shell O(a)-improved chiral fermion action: We perform a study the quark-gluon vertex function with a quenched Wilson gauge action and a variety of fermion actions. These include the domain wall fermion action (with exponentially accurate chiral symmetry) and the Wilson clover action both ...
hep-lat
Frontiers of finite temperature lattice QCD: I review a selection of recent finite temperature lattice results of the past years. First I discuss the extension of the equation of state towards high temperatures and fi- nite densities, then I show recent results on the QCD topological susceptibility at high temperatures...
hep-lat
Recent results in high temperature lattice gauge theories: We review some analytic results on the deconfinement transition in pure lattice gauge theories. In particular we discuss the relationship between the deconfinement transition in the $(d+1)$-dimensional $SU(2)$ model and the magnetization transition in the $d$-d...
hep-lat
Non-perturbative parton mass for the gluon: A gauge invariant, non-local observable is constructed in pure gauge theory, which is identical to the gluon propagator in a particular gauge, permitting to define a non-perturbative parton mass for the gluon. This mass can be shown to be related to the 1P-1S mass splitting o...
hep-lat
Subtleties and Fancies in Gauge Theory Non Trivial Vacuum: The one loop effective potential for a non-Abelian gauge configuration is analyzed using the background field method. The Savvidy result and the non-Abelian ansatz, the other alternative possible background that generates a constant color magnetic field configu...
hep-lat
The Weak-Coupling Limit of 3D Simplicial Quantum Gravity: We investigate the weak-coupling limit, kappa going to infinity, of 3D simplicial gravity using Monte Carlo simulations and a Strong Coupling Expansion. With a suitable modification of the measure we observe a transition from a branched polymer to a crinkled pha...
hep-lat
The three-dimensional, three-state Potts Model in an External Field: We analyze the critical behaviour of the three-dimensional, three-state Potts model in the presence of an external ordering field. From a finite size scaling analysis on lattices of size up to 70**3 we determine the critical endpoint of the line of fi...
hep-lat
Color Structure of Gluon Field Magnetic Mass: The color structure of the gluon field magnetic mass is investigated in the lattice SU(2) gluodynamics. To realize that, the interaction between a monopole-antimonopole string and external neutral Abelian chromomagnetic field flux is considered. The string is introduced in ...
hep-lat
Polyakov loop fluctuations in SU(3) lattice gauge theory and an effective gluon potential: We calculate the Polyakov loop susceptibilities in the SU(3) lattice gauge theory using the Symanzik improved gauge action on different-sized lattices. The longitudinal and transverse fluctu- ations of the Polyakov loop, as wel...
hep-lat
Color screening potential at finite density in two-flavor lattice QCD with Wilson fermions: We investigate chemical-potential (\mu) dependence of static-quark free energies in both the real and imaginary \mu regions, performing lattice QCD simulations at imaginary \mu and extrapolating the results to the real \mu reg...
hep-lat
The chiral phase transition for QCD with sextet quarks: QCD with 2 massless colour-sextet quarks is studied as a model of Walking Technicolor. We simulate lattice QCD with 2 light color-sextet staggered quarks at finite temperature, and use the dependence of the coupling at the chiral transition on the temporal extent,...
hep-lat
$B_s \to K \ell ν$ form factors from lattice QCD: We report the first lattice QCD calculation of the form factors for the standard model tree-level decay $B_s\to K \ell\nu$. In combination with future measurement, this calculation will provide an alternative exclusive semileptonic determination of $|V_{ub}|$. We compar...
hep-lat
Low-energy Scattering and Effective Interactions of Two Baryons at $m_π\sim 450$ MeV from Lattice Quantum Chromodynamics: The interactions between two octet baryons are studied at low energies using lattice QCD (LQCD) with larger-than-physical quark masses corresponding to a pion mass of $m_{\pi}\sim 450$ MeV and a k...
hep-lat
Heavy quark free energies for three quark systems at finite temperature: We study the free energy of static three quark systems in singlet, octet, decuplet and average color channels in the quenched approximation and in 2-flavor QCD at finite temperature. We show that in the high temperature phase singlet and decuplet ...
hep-lat
Axial Charges of Octet Baryons in Two-flavor Lattice QCD: We evaluate the strangeness-conserving $N N$, $\Sigma\Sigma$, $\Xi\Xi$, $\Lambda\Sigma$ and the strangeness-changing $\Lambda N$, $\Sigma N$, $\Lambda\Xi$, $\Sigma\Xi$ axial charges in lattice QCD with two flavors of dynamical quarks and extend our previous work...
hep-lat
f_B and the Heavy-light Spectrum from NRQCD: The present status of lattice calculations of the B spectrum and f_B, using NRQCD for the b quark, is discussed.
hep-lat
CL2QCD - Lattice QCD based on OpenCL: We present the Lattice QCD application CL2QCD, which is based on OpenCL and can be utilized to run on Graphic Processing Units as well as on common CPUs. We focus on implementation details as well as performance results of selected features. CL2QCD has been successfully applied in ...
hep-lat
The (LATTICE) QCD Potential and Running Coupling: How to Accurately Interpolate between Multi-Loop QCD and the String Picture: We present a simple parameterization of a running coupling constant, defined via the static potential, that interpolates between 2-loop QCD in the UV and the string prediction in the IR. Besi...
hep-lat
The QCD Equation of State: Results for the equation of state in 2+1 flavor QCD at zero net baryon density using the Highly Improved Staggered Quark (HISQ) action by the HotQCD collaboration are presented. The strange quark mass was tuned to its physical value and the light (up/down) quark masses fixed to $m_l = 0.05m_s...
hep-lat
Chiral gauge theories on the lattice without gauge fixing?: We discuss two proposals for a non-perturbative formulation of chiral gauge theories on the lattice. In both cases gauge symmetry is broken by the regularization. We aim at a dynamical restoration of symmetry. If the gauge symmetry breaking is not too severe t...
hep-lat
Higgs boson mass bounds in the presence of a very heavy fourth quark generation: We study the effect of a potential fourth quark generation on the upper and lower Higgs boson mass bounds. This investigation is based on the numerical evaluation of a chirally invariant lattice Higgs-Yukawa model emulating the same Higg...
hep-lat
Pion Polarizabilities and Volume Effects in Lattice QCD: We use chiral perturbation theory to study the extraction of pion electromagnetic polarizabilities from lattice QCD. Chiral extrapolation formulae are derived for partially quenched QCD, and quenched QCD simulations. On a torus, volume dependence of electromagnet...
hep-lat
Spectral functions at small energies and the electrical conductivity in hot, quenched lattice QCD: In lattice QCD, the Maximum Entropy Method can be used to reconstruct spectral functions from euclidean correlators obtained in numerical simulations. We show that at finite temperature the most commonly used algorithm,...
hep-lat
Calculation of $ρ$ meson decay width from the PACS-CS configurations: We present preliminary results on the $\rho$ meson decay width from $N_f=2+1$ full QCD configurations generated by PACS-CS Collaboration. The decay width is estimated from the $P$-wave scattering phase shift for the isospin $I=1$ two-pion system. The...
hep-lat
Testing universality and the fractional power prescription for the staggered fermion determinant: In [Phys.Rev.Lett.92:162002 (2004), hep-lat/0312025] expressions for the continuous Euclidean time limits of various lattice fermion determinants were derived and compared in order to test universality expectations in La...
hep-lat
Fast algorithms for simulating chiral fermions in U(1)lattice gauge theory: In order to develop fast inversion algorithms we have used overlap solvers in two dimensions. Lattice QED theory with U(1) group symmetry in two dimensional space-times dimensions has always been a testing ground for algorithms. By the other ...
hep-lat
Formulation of chiral gauge theories: We present a formulation of chiral gauge theories, which admits more general spectra of Dirac operators and reveals considerably more possibilities for the structure of the chiral projections. Our two forms of correlation functions both also apply in the presence of zero modes and ...
hep-lat
Center-symmetric dimensional reduction of hot Yang-Mills theory: It is expected that incorporating the center symmetry in the conventional dimensionally reduced effective theory for high-temperature SU(N) Yang-Mills theory, EQCD, will considerably extend its applicability towards the deconfinement transition. The const...
hep-lat
Radially Excited States of 1P Charmonia and X(3872): The excited states of charmonia are numerically investigated in quenched lattice QCD with improved gauge and Wilson fermion actions formulated on anisotropic lattices. Through a constrained curve fitting algorithm, the masses of the first excited states in $0^{++}$, ...
hep-lat
Three-Flavor Partially Quenched Chiral Perturbation Theory at NNLO for Meson Masses and Decay Constants: We discuss Partially Quenched Chiral Perturbation Theory (PQ$\chi$PT) and possible fitting strategies to Lattice QCD data at next-to-next-to-leading order (NNLO) in the mesonic sector. We also present a complete c...
hep-lat
Axial Anomaly in Lattice Abelian Gauge Theory in Arbitrary Dimensions: Axial anomaly of lattice abelian gauge theory in hyper-cubic regular lattice in arbitrary even dimensions is investigated by applying the method of exterior differential calculus. The topological invariance, gauge invariance and locality of the axia...
hep-lat
The finite temperature transition for 3-flavour lattice QCD at finite isospin density: We simulate 3-flavour lattice QCD with a small chemical potential $\mu_I$ for isospin, at temperatures close to the finite temperature transition. Using quark masses just above the critical mass for zero chemical potential, we dete...
hep-lat
Physics From Breit-Frame Regularization Of a Lattice Hamiltonian: We suggest a Hamiltonian formulation on a momentum lattice using a physically motivated regularization using the Breit-frame which links the maximal parton number to the lattice size. This scheme restricts parton momenta to positive values in each spatia...
hep-lat
Stabilizing the electroweak vacuum by higher dimensional operators in a Higgs-Yukawa model: The Higgs boson discovery at the LHC with a mass of approximately 126 GeV suggests, that the electroweak vacuum of the standard model may be metastable at very high energies. However, any new physics beyond the standard model ...
hep-lat
The chiral transition in two-flavor QCD: QCD with N_f=2 is a specially interesting system to investigate the chiral transition. The order of the transition has still not been established. We report the results of an in-depth numerical investigation performed with staggered fermions on lattices with L_t=4 and L_s=12,16,...
hep-lat
Nucleon form factors and structure functions with N_f=2+1 dynamical domain wall fermions: We report isovector form factors and low moments of structure functions of nucleon in numerical lattice quantum chromodynamics (QCD) from the on-going calculations by the RIKEN-BNL-Columbia (RBC) and UKQCD Collaborations with (2...
hep-lat
Form factor for Dalitz decays from $J/ψ$ to light pseudoscalars: We calculate the form factor $M(q^2)$ for the Dalitz decay $J/\psi\to \gamma^*(q^2)\eta_{(N_f=1)}$ with $\eta_{(N_f)}$ being the SU($N_f$) flavor singlet pseudoscalar meson. The difference among the partial widths $\Gamma(J/\psi\to \gamma \eta_{(N_f)})$ a...
hep-lat
Noise, sign problems, and statistics: We show how sign problems in simulations of many-body systems can manifest themselves in the form of heavy-tailed correlator distributions, similar to what is seen in electron propagation through disordered media. We propose an alternative statistical approach for extracting ground...
hep-lat
The critical end point in QCD: In this talk I present the logic behind, and examine the reliability of, estimates of the critical end point (CEP) of QCD using the Taylor expansion method.
hep-lat
The principle of indirect elimination: The principle of indirect elimination states that an algorithm for solving discretized differential equations can be used to identify its own bad-converging modes. When the number of bad-converging modes of the algorithm is not too large, the modes thus identified can be used to s...
hep-lat
Excited mesons from $N_f=2$ dynamical Clover Wilson lattices: We study mesons on the lattice with a special focus on excited states. For that purpose we construct several quark sources with different spatial smearings, including p-waves. These quark sources are then combined with the appropiate Dirac structures to form...
hep-lat
$B_K$ with improved staggered fermions: analysis using SU(2) staggered chiral perturbation theory: We report updated results for $B_K$ calculated using HYP-smeared staggered fermions on the MILC asqtad 2+1 flavor lattices. We use four different lattice spacings ($a \approx$ 0.12, 0.09, 0.06 and 0.045 fm) to control t...
hep-lat
Critical Exponents of the 3D Ising Universality Class From Finite Size Scaling With Standard and Improved Actions: We propose a method to obtain an improved Hamiltonian (action) for the Ising universality class in three dimensions. The improved Hamiltonian has suppressed leading corrections to scaling. It is obtained...
hep-lat
The QCD phase diagram at nonzero quark density: We determine the phase diagram of QCD on the \mu-T plane for small to moderate chemical potentials. Two transition lines are defined with two quantities, the chiral condensate and the strange quark number susceptibility. The calculations are carried out on N_t =6,8 and 10...
hep-lat
The $ρ$-resonance with physical pion mass from $N_f=2$ lattice QCD: We present the first-ever lattice computation of pi pi-scattering in the I=1 channel with Nf=2 dynamical quark flavours obtained including an ensemble with physical value of the pion mass. Employing a global fit to data at three values of the pion mass...
hep-lat
The Charmonium Potential at Non-Zero Temperature: The potential between charm and anti-charm quarks is calculated non-perturbatively using physical, rather than static quarks at temperatures on both sides of the deconfinement transition $T_{\rm C}$, using a lattice simulation with 2+1 dynamical quark flavours. We used ...
hep-lat
A Study of the $N=2$ Kazakov-Migdal Model: We study numerically the SU(2) Kazakov-Migdal model of `induced QCD'. In contrast to our earlier work on the subject we have chosen here {\it not} to integrate out the gauge fields but to keep them in the Monte Carlo simulation. This allows us to measure observables associated...
hep-lat
Lattice Artefacts In The Non-Abelian Debye Screening Mass In One Loop Order: We compute the electric screening mass in lattice QCD with Wilson fermions at finite temperature and chemical potential to one-loop order, and show that lattice artefacts arising from a finite lattice spacing result in an enhancement of the ...
hep-lat
$O(a^2)$-improved actions for heavy quarks and scaling studies on quenched lattices: We investigate a new class of improved relativistic fermion action on the lattice with a criterion to give excellent energy-momentum dispersion relation as well as to be consistent with tree-level $O\left(a^{2}\right)$-improvement. M...
hep-lat
Excited States of U(1)$_{2+1}$ Lattice Gauge Theory from Monte Carlo Hamiltonian: We address an old problem in lattice gauge theory - the computation of the spectrum and wave functions of excited states. Our method is based on the Hamiltonian formulation of lattice gauge theory. As strategy, we propose to construct a...
hep-lat
THE QCD ABACUS: A New Formulation for Lattice Gauge Theories: A quantum Hamiltonian is constructed for SU(3) lattice QCD entirely from color triplet Fermions --- the standard quarks and a new Fermionic ``constituent'' of the gluon we call ``rishons''. The quarks are represented by Dirac spinors on each site and the gau...
hep-lat
Numerical tests of the electroweak phase transition and thermodynamics of the electroweak plasma: The finite temperature phase transition in the SU(2) Higgs model at a Higgs boson mass $M_H \simeq 34$ GeV is studied in numerical simulations on four-dimensional lattices with time-like extensions up to $L_t=5$. The eff...
hep-lat
Landau gauge gluon and ghost propagators from two-flavor lattice QCD at T > 0: In this contribution we extend our unquenched computation of the Landau gauge gluon and ghost propagators in lattice QCD at non-zero temperature. The study was aimed at providing input for investigations employing continuum functional meth...
hep-lat
Massless Fermions on the Lattice: We consider a nonlocal lattice action for fermions fermion doubling in lattice theories. It is shown, that it is possible to avoid the fermionic doubling in the case of free fermions, but this approach does not reproduce results for the effective action for gauge fields in the continuu...
hep-lat
The pion form factor on the lattice at zero and finite temperature: We calculate the electromagnetic form factor of the pion in quenched lattice QCD. The non-perturbatively improved Sheikoleslami-Wohlert lattice action is used together with the consistently O(a) improved current. We calculate the pion form factor for m...
hep-lat
Disconnected contributions to D-meson semi-leptonic decay form factors: We calculate the disconnected contribution to the form factor for the semileptonic decay of a D-meson into a final state, containing a flavor singlet eta meson. We use QCDSF n_f=2+1 configurations at the flavor symmetric point m_u=m_d=m_s and the p...
hep-lat
Finite Size Scaling and ``perfect'' actions: the three dimensional Ising model: Using Finite-Size Scaling techniques, we numerically show that the first irrelevant operator of the lattice $\lambda\phi^4$ theory in three dimensions is (within errors) completely decoupled at $\lambda=1.0$. This interesting result also ...
hep-lat
K \to ππdecay amplitudes from the lattice: In order to directly compute physical two-pion K-decay amplitudes using lattice methods we must prepare a two-pion state with non-zero relative momentum. Building upon a proposal of Lellouch and L\"uscher, we describe a finite-volume method to realize such a state as the lowes...
hep-lat
Linear broadening of the confining string in Yang-Mills theory at low temperature: The logarithmic broadening predicted by the systematic low-energy effective field theory for the confining string has recently been verified in numerical simulations of (2+1)-d SU(2) lattice Yang-Mills theory at zero temperature. The s...
hep-lat
Accelerating lattice QCD simulations with 2 flavours of staggered fermions on multiple GPUs using OpenACC - a first attempt: We present the results of an effort to accelerate a Rational Hybrid Monte Carlo (RHMC) program for lattice quantum chromodynamics (QCD) simulation for 2 flavours of staggered fermions on multip...
hep-lat
Phase diagram of QCD in strong background magnetic field: We discuss the phase diagram of QCD in the presence of a strong background magnetic field, providing numerical evidence, based on lattice simulations of QCD with $2+1$ flavours and physical quark masses, that the QCD crossover turns into a first order phase tran...
hep-lat
Gauge Invariance and Confinement in Noncompact Simulations of SU(2): Wilson loops have been measured at strong coupling, $\beta=0.5$, on a $12^4$ lattice in a noncompact simulation of pure SU(2) in which random compact gauge transformations impose a kind of lattice gauge invariance. The Wilson loops suggest a confining...
hep-lat
The 't Hooft-Veneziano limit of the Polyakov loop models: The broad class of U(N) and SU(N) Polyakov loop models on the lattice are solved exactly in the combined large N, Nf limit, where N is a number of colors and Nf is a number of quark flavors, and in any dimension. In this 't Hooft-Veneziano limit the ratio N/Nf i...
hep-lat
Charmonium Potentials at Finite Temperature: The charmonium states at non-zero temperature are studied on anisotropic lattices with 2 dynamical quark flavours. Non-local operators are used to determine the Nambu-Bethe-Salpeter (NBS) wavefunctions via both conventional fitting methods and the Maximum Entropy Method. The...
hep-lat
A Connection Between Complex-Temperature Properties of the 1D and 2D Spin $s$ Ising Model: Although the physical properties of the 2D and 1D Ising models are quite different, we point out an interesting connection between their complex-temperature phase diagrams. We carry out an exact determination of the complex-tem...
hep-lat
Repairing Stevenson's step in the 4d Ising model: In a recent paper Stevenson claimed that analysis of the data on the wave function renormalization constant near the critical point of the 4d Ising model is not consistent with analytical expectations. Here we present data with improved statistics and show that the resu...
hep-lat
High Spin Glueballs from the Lattice: We discuss the principles underlying higher spin glueball calculations on the lattice. For that purpose, we develop numerical techniques to rotate Wilson loops by arbitrary angles in lattice gauge theories close to the continuum. As a first application, we compute the glueball spec...
hep-lat