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Prof. Kieran Holland (University of the Pacific)15/07/2015, 18:30Theoretical DevelopmentsPosterWe describe a new method to determine in a stochastic fashion the Dirac operator spectral density over the entire range of eigenvalues. This allows for example studies of the chiral limit of the fermion condensate, the mode number and the anomalous mass dimension. We apply this technique to the 2-flavor sextet SU(3) gauge theory, to investigate this theory's viability as a minimal...Go to contribution page
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Prof. Leonardo Giusti (University of Milano Bicocca)15/07/2015, 18:30Nonzero Temperature and DensityPosterWe present an accurate computation of the Equation of State of SU(3) Yang-Mills theory using shifted boundary conditions in the temporal direction. In this framework, the entropy density s(T) can be obtained in a simple way from the v.e.v. of the space-time components T_0k of the energy-momentum tensor. Furthermore, contrary to the standard approach, the Equation of State s(T)/T^3 can be...Go to contribution page
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Prof. Tilo Wettig (University of Regensburg)15/07/2015, 18:30Algorithms and MachinesPosterWe present details of our implementation of the Wuppertal adaptive algebraic multigrid code on SIMD architectures, with particular emphasis on the Intel Xeon Phi processor (KNC) used in QPACE 2. As a smoother, the algorithm uses a domain-decomposition-based solver code previously developed for the KNC in Regensburg. We optimized the remaining parts of the multigrid code and conclude...Go to contribution page
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Prof. Tetsuya Takaishi (Hiroshima University of Economics), Prof. Yubin Liu (Nankai University)15/07/2015, 18:30Algorithms and MachinesPosterThe hybrid Monte Carlo (HMC) algorithm has been widely used for dynamical lattice QCD simulations. One of the advantages of using the HMC algorithm is that it is a global algorithm that can update all link variables simultaneously. In this way we can greatly reduce computational cost concerning the fermionic part. We utilize this advantage for parameter estimations of the realized stochastic...Go to contribution page
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Prof. Atsushi Nakamura (RCNP, Osaka Univ.)15/07/2015, 18:30Nonzero Temperature and DensityPosterAt finite density lattice QCD, the famous sign problem has prevented us from studying the QCD phase diagram based on the first-principle calculation. In order to circumvent the problem, we propose a method where we put new wine into old wineskins: i.e., we use an old idea, "canonical approach", but put into it a new ingredient, multi-precision calculations. This is free from the usual...Go to contribution page
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Ms Aya Kagimura (Particle Physics Theory Group, Department of Physics, Osaka university)15/07/2015, 18:30Applications Beyond QCDPosterAround a large charge with atomic number Z > 137, the QED vacuum is expected to collapse due to the strong Coulombic force. While the relativistic quantum mechanics fails to make reliable predictions for the fate of the vacuum, the heavy ion collision experiment also does not give clear understanding of this system. Recently,the "atomic collapse" resonances were observed on graphene where...Go to contribution page
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Mr Hwancheol Jeong (Seoul National University)15/07/2015, 18:30Chiral SymmetryPosterWe calculate the strange quark condensate and the light quark condensate by using improved staggered fermions and overlap fermions, respectively. Then we report the mass dependence of the quark condensate. We use N_f = 2+1+1 MILC HISQ(highly improved staggered quark) gauge ensembles. We use a normal CG inverter to calculate the quark condensates for higher quark masses, and the Lanczos and the...Go to contribution page
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Prof. Weonjong Lee (Seoul National University)15/07/2015, 18:30Weak Decays and Matrix ElementsPosterWe present the Standard Model evaluation of the indirect CP violation parameter $\varepislon_K$ determined using lattice QCD inputs: $\hat{B}_K$, $\xi_0$, $V_{us}$, and $V_{cb}$. We find that the Standard Model prediction of $\varepsilon_K$ with exclusive $V_{cb}$ (lattice QCD results) is lower than the experimental value by $3.6\sigma$. However, this tension disappears with inclusive...Go to contribution page
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Dr Stephan Durr (Wuppertal University / JSC Julich)15/07/2015, 18:30Standard Model Parameters and RenormalizationPosterPreliminary results are presented from a new determination of f_K/f_pi which is based on a series of staggered Nf=2+1+1 simulations in the vicinity of the physical point. Special emphasis is put on the interpolation to the physical point, the finite-volume corrections, the continuum extrapolation and the breaking of the isospin symmetry.Go to contribution page
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Richard Woloshyn (TRIUMF)15/07/2015, 18:30Hadron Spectroscopy and InteractionsPosterFree-form smearing was designed as a way to implement source operators of any desired shape. A variation of the method is introduced that reduces the computational cost by reducing the number of link multiplications to its absolute minimum. Practical utility is demonstrated through calculations of bottomonium and B meson masses.Go to contribution page
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Yusuke Yoshimura (RIKEN Advanced Institute for Computational Science)15/07/2015, 18:30Nonzero Temperature and DensityPosterIn numerical calculation of the lattice QCD, the sign problem of Monte Carlo methods has been a major issue. A numerical renormalization group called tensor renormalization group (TRG) is one of the candidates for the solution of this problem. Grassmann tensor renormalization group (GTRG) is a generalization of the TRG to fermion systems. In this study, We apply the GTRG to the lattice...Go to contribution page
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Dr Azusa Yamaguchi (University of Edinburgh)15/07/2015, 18:30Algorithms and MachinesPosterWe discuss progress and performance from the development of the Grid data parallel interface for cartesian fields of tensor data types. The library is suitable for the simulation of QCD including multiple grids. Wherever appropriate the interface is quite similar to that of QDP++, but the library makes use of C++11 features to reduce the volume of code, compared to QDP++ while...Go to contribution page
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Mr JAEHOON LEEM (Seoul National University)15/07/2015, 18:30Weak Decays and Matrix ElementsPosterWe improve heavy-heavy currents for calculating B ̅ →D^((*) ) lν ̅ semi-leptonic form factors with Oktay-Kronfeld (OK) heavy quarks. The OK action, which has dimension 6 and 7 interaction terms, can control the discretization errors of heavy quarks (b and c quarks). The OK action is improved through third order in HQET power counting. We report work on heavy-heavy currents to get the...Go to contribution page
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Mr Marco garofalo (The University of Edinburgh)15/07/2015, 18:30Theoretical DevelopmentsPosterL\"uscher recently introduced Instantaneous Stochastic Perturbation Theory (ISPT) as a method for the stochastic evaluation of lattice perturbation theory. We present an exploratory study of its properties in $\phi^4$ theory, and we compare it with both analytical computations and Numerical Stochastic Perturbation Theory. In addition, we propose a automated method based on ISPT for solution of...Go to contribution page
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Dr Craig McNeile (Plymouth University)15/07/2015, 18:30Hadron Spectroscopy and InteractionsPosterPreliminary results for the effect of open boundary conditions on the masses of glueballs and the probability distributions of glueball correlators, in quenched QCD, are presented. Initial results from glueball correlators computed on unquenched ensembles downloaded from the ILDG data grid are reported.Go to contribution page
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Prof. Gernot Münster (University of Münster)15/07/2015, 18:30Chiral SymmetryPosterWe present the expansions of the masses of the pseudoscalar mesons in chiral perturbation theory at next-to-leading order for twisted mass lattice QCD with three light quark flavours, taking the mass difference between the up and down quarks into account.Go to contribution page
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Dr Shinji Motoki (High Energy Accelerator Research Organization(KEK))15/07/2015, 18:30Algorithms and MachinesPosterWe are developing a code set "Bridge++" for simulations of lattice gauge theories that aims at an extensible, readable, and portable workbench, while achieving high performance. This work concerns the design of Bridge++ to incorporate the accelerator devices, such as GPUs. As generic frameworks for heterogeneous programming using CPU and accelerator devices, we apply OpenCL and OpenACC to...Go to contribution page
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Mr Masayuki Wakayama (Nagoya University)15/07/2015, 18:30Hadron Spectroscopy and InteractionsPosterWe study the possible significance of four-quark states in the isosinglet scalar mesons ($J^{PC}=0^{++}$, I=0) by performing two-flavor full lattice QCD simulations on an $8^3 ¥times 16$ lattice using the improved gauge action and the clover-improved Wilson quark action. In particular, we evaluate the propagators of molecular and tetraquark operators together with singly disconnected diagrams....Go to contribution page
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Mr Ken-Ichi Ishikawa (Hiroshima University, Department of Physical Science)15/07/2015, 18:30Standard Model Parameters and RenormalizationPosterWe present the quark mass and axial current renormalization factors for the RG-improved gauge and the stout smeared $O(a)$-improved Wilson quark actions. The $O(a)$ improvement coefficient for the three-flavors of dynamical quarks has been determined previously with the stout-link smearing parameter $\alpha=0.1, n=6$. We employ the Schr\"{o}dinger functional scheme and obtain the...Go to contribution page
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Mr Joni Suorsa (University of Helsinki, Helsinki Institute of Physics)15/07/2015, 18:30Physics Beyond the Standard ModelPosterSU2 with Nf=8 is believed to have an infrared conformal fixed point. We use the spectral density method to evaluate the coupling constant dependence of the mass anomalous dimension. We use massless theory with Schrödinger functional boundary conditions and HEX smeared Wilson clover fermions.Go to contribution page
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Prof. Takehiro Azuma (Setsunan University)15/07/2015, 18:30Theoretical DevelopmentsPosterThe IIB matrix model has been proposed as a nonperturbative definition of superstring theory. In this work, we study the Euclidean version of this model in which extra dimensions can be dynamically compactified if a scenario of the spontaneous breakdown of the SO(10) rotational symmetry is realized. Monte Carlo calculations of the Euclidean IIB matrix model suffer from a very strong complex...Go to contribution page
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Mr Daniel Richtmann (University of Regensburg)15/07/2015, 18:30Algorithms and MachinesPosterThe setup cost of a modern solver such as the DD-$\alpha$AMG (Wuppertal Multigrid) is a significant contribution to the total time spent on solving the Dirac equation, and in HMC it can even be dominant. We present an improved implementation of this algorithm with modified computation order in the setup procedure. By processing multiple right-hand sides simultaneously we can alleviate many of...Go to contribution page
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Dr jangho Kim (Korea Institute of Science and Technology Information)15/07/2015, 18:30Standard Model Parameters and RenormalizationPosterWe present the preliminary results of the wave function renormalization factor Z_q and mass renormalization factor Z_m from the bilinear operators obtained using non-perturbative renormalization method(NPR) in the RI-MOM scheme with improved staggered fermions. We use fine ensembles of MILC asqtad lattices (N_f=2+1) with 28^3 \times 96 geometry and am_\ell / am_s = 0.0062 / 0.031. We also...Go to contribution page
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Dr Nigel Cundy (Seoul National University)15/07/2015, 18:30Algorithms and MachinesPosterWe report on our efforts to impliment overlap fermions on NVIDIA GPUs using CUDA, commenting on the algorithms used, implemetation details, and the performance of our code.Go to contribution page
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Mr Jeonghwan Pak (Seoul National University)15/07/2015, 18:30Algorithms and MachinesPosterMatching factors for the four-fermion operators relevant to B_K are obtained using the Non-Perturbative Renormalization(NPR) method in the RI-MOM scheme. Our NPR codes are calculated in Double Precision(DP) and optimized on Fermi GPU. NVIDIA released The GTX Titan X based on the Maxwell architecture. The Single Precision(SP) calculation performance of the GTX Titan X is improved, but the ratio...Go to contribution page
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Dr Andreas Juettner (University of Southampton)15/07/2015, 18:30Algorithms and MachinesPosterWith the aim of studying the relevance and properties of critical slowing down in Monte Carlo simulations of lattice quantum field theories we carried out a high precision numerical study of the discretised two-dimensional CP^{N-1} model at N=10 using an over-heat bath algorithm. We identify critical slowing down in terms of slowly-evolving topological modes and present evidence that other...Go to contribution page
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Prof. Wolfgang Bietenholz (Universidad Nacional Autonoma de Mexico)15/07/2015, 18:30Theoretical DevelopmentsPosterThe 2d CP(N-1) models share a number of features with QCD, like asymptotic freedom, a dynamically generated mass gap, and topological sectors. They have been formulated and analysed successfully in the formalism of the so-called D-theory. In that framework, we propose an experimental set-up for the quantum simulation of the CP(2) model. It is based on ultracold alkaline-earth-atoms...Go to contribution page
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Prof. Ming Gong (Institute of High Energy Physics, CAS)15/07/2015, 18:30Hadron StructurePosterWe report a quark spin calculation from the anomalous Ward identity with overlap fermions on 2+1 flavor dynamical fermion configurations. Such a formulation decomposes the divergence of the flavor-singlet axial-vector current into a quark pseudoscalar term and a triangle anomaly term, flavor by flavor. We use the overlap fermion for the valence and the quark loop so that the renormalization...Go to contribution page
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Yasumichi Aoki (KMI, Nagoya University)15/07/2015, 18:30Physics Beyond the Standard ModelPosterSU(3) gauge theory with eight massless fundamental fermions seems to be near the conformal boundary, and is a candidate of walking technicolor. Along the series of study by LatKMI collaboration using HISQ fermions, S-parameter and vector decay constant, which provide important constraints in the model building, are calculated for this theory. Use of various volumes allows a systematic...Go to contribution page
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Prof. Shoji Hashimoto (KEK)15/07/2015, 18:30Chiral SymmetryPosterWe calculate the spectral function of the QCD Dirac operator using the four-dimensional effective operator constructed from the Mobius domain-wall implementation. We utilize the eigenvalue filtering technique combined with the stochastic estimate of the mode number. The spectrum in the entire eigenvalue range is obtained with a single set of measurements. Results on 2+1-flavor ensembles with...Go to contribution page
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Mr Marcin Szyniszewski (Lancaster University)15/07/2015, 18:30Applications Beyond QCDPosterWe employ a strong coupling expansion - similar to the one used in the lattice field theory studies [1] - to solve the one-dimensional extended t-V model of fermions on a lattice [2]. This model is solved for a range of filling factors, including both commensurate - where a charge density wave is present - and incommensurate densities. The first set consists not only of a trivial case of half...Go to contribution page
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Dr Jun Noaki (KEK)15/07/2015, 18:30Theoretical DevelopmentsPosterWe study the vacuum structure of the SU(3) gauge theory with the flavor number within the conformal region. We perform numerical simulation employing the massless Domain-Wall fermions with the one-step stout smearing. We investigate a conjecture based on the idea of "the conformal field theories with an IR cutoff", which was recently studied using the Wilson fermions. Dealing with the...Go to contribution page
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Dr Hideo Matsufuru (High Energy Accelerator Research Organization (KEK))15/07/2015, 18:30Applications Beyond QCDPosterWe study the SU(2) gauge theory with dynamical domain-wall fermions in fundamental and adjoint representations. Dynamical simulations with fundamental fermions are performed with numbers of flavors Nf=2,4,6, and 8. Nf dependence of the meson masses and decay constants are investigated. The same analyses are applied also to the adjoint fermions, based on the investigation of the Aoki...Go to contribution page
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Mr Thomas Kloiber (University of Graz)15/07/2015, 18:30Nonzero Temperature and DensityPosterWe study the two dimensional nonlinear O(3) model with a chemical potential coupled to the conserved charge. The complex action problem occurring at nonzero chemical potential is solved by means of a duality transform, which yields real and positive weights and makes Monte Carlo simulations feasible. We find a phase transition at the end of a Silver Blaze region, where a net number of...Go to contribution page
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Ms Yuko Murakami (Hiroshima University)15/07/2015, 18:30Theoretical DevelopmentsPosterLast year we reported the property of the the Moebius Domain Wall Fermions (MDWF) in the Schroedinger Functional (SF) scheme with the palindromic fifth dimensional parameters and the appropriate boundary operator at the tree-level, and the non-universal behavior for a small fifth direction extent $N_5$. We find that this behavior comes from the residual mass at the tree-level and the...Go to contribution page
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Mr Markus Werner (University of Bonn)15/07/2015, 18:30Hadron Spectroscopy and InteractionsPosterWe present first results for I=1 pipi scattering with N_f=2+1+1 twisted mass fermions utilizing the sLapH method. The rho mass and decay width are computed for various pion masses and lattice spacings. Special care was taken in the analysis of systematic uncertainties.Go to contribution page
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Dr Miho Koma (Nihon University, College of International Relations)15/07/2015, 18:30Vacuum Structure and ConfinementPosterWe study the static three-quark potential in SU(3) lattice gauge theory at zero temperature with the Polyakov loop correlation function consisting of three Polyakov loops. By employing the multi-level algorithm we overcome the smallness of the signal to noise ratio and obtain remarkably clean signals. We extend our previous investigation of the three-quark potential and compute the...Go to contribution page
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Dr Anna Hasenfratz (University of Colorado)15/07/2015, 18:30Physics Beyond the Standard ModelPosterWe investigate the discrete $\beta$ function of the 2-flavor SU(3) sextet model using the gradient flow scheme. Staggered fermion investigations suggest that the system is chirally broken, contradicting earlier Schroedinger functional Wilson fermion studies that were consistent with conformality. Our results, using improved Wilson fermions and the gradient flow RG scheme, suggests a step...Go to contribution page
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Vanessa Koch (Trinity College Dublin)15/07/2015, 18:30Hadron Spectroscopy and InteractionsPosterWe investigate the use of stochastically estimated light quark propagators in correlation functions involving a static color source. To this end we compute the static-light meson correlation function in the stochastic LapH framework, using N_f= 2+1 gauge configurations generated through the CLS effort. Together with the static potential, we obtain an estimate for the expected string breaking distance.Go to contribution page
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Dr Takashi Umeda (Hiroshima University)15/07/2015, 18:30Nonzero Temperature and DensityPosterWe study the $N_f=2+1$ QCD at nonzero temperatures using nonperbatively improved Wilson quarks of the physical masses by the fixed scale approach. We perform physical point simulations at finite temperatures with the coupling parameters which were adopted by the PACS-CS collaboration in their studies using the reweighting technique. Zero temperature values are obtained on the PACS-CS...Go to contribution page
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Mr Yong-Chull Jang (Seoul National University)15/07/2015, 18:30Hadron Spectroscopy and InteractionsPosterWe present updated results of the heavy-meson spectrum obtained using the Oktay--Kronfeld (OK) action on MILC asqtad lattices. The OK action was designed to improve the heavy-quark action of the Fermilab formulation by including complete dimension six and part of dimension seven bilinear improvement terms. Improvement terms are truncated by power counting of order $\Lambda^3/m^3$ for...Go to contribution page
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