scholarly journals MANY MASSES ON ONE STROKE: ECONOMIC COMPUTATION OF QUARK PROPAGATORS

1995 ◽  
Vol 06 (05) ◽  
pp. 627-638 ◽  
Author(s):  
ANDREAS FROMMER ◽  
BERTOLD NÖCKEL ◽  
STEPHAN GÜSKEN ◽  
THOMAS LIPPERT ◽  
KLAUS SCHILLING
Keyword(s):  
Mass Matrix ◽  
Computational Effort ◽  
Lattice Quantum Chromodynamics ◽  
Normal Equations ◽  
Wilson Fermion ◽  
Quark Masses ◽  
Lanczos Process ◽  
Lattice Quantum ◽  
Minimal Residual ◽  
Better Than

The computational effort in the calculation of Wilson fermion quark propagators in Lattice Quantum Chromodynamics can be considerably reduced by exploiting the Wilson fermion matrix structure in inversion algorithms based on the non-symmetric Lanczos process. We consider two such methods: QMR (quasi minimal residual) and BCG (biconjugate gradients). Based on the decomposition M/κ = 1/κ−D of the Wilson mass matrix, using QMR, one can carry out inversions on a whole trajectory of masses simultaneously, merely at the computational expense of a single propagator computation. In other words, one has to compute the propagator corresponding to the lightest mass only, while all the heavier masses are given for free, at the price of extra storage. Moreover, the symmetry γ5M = M†γ5 can be used to cut the computational effort in QMR and BCG by a factor of two. We show that both methods then become — in the critical regime of small quark masses — competitive to BiCGStab and significantly better than the standard MR method, with optimal relaxation factor, and CG as applied to the normal equations.

scholarly journals ACCELERATING WILSON FERMION MATRIX INVERSIONS BY MEANS OF THE STABILIZED BICONJUGATE GRADIENT ALGORITHM

1994 ◽  
Vol 05 (06) ◽  
pp. 1073-1088 ◽  
Author(s):  
ANDREAS FROMMER ◽  
VOLKER HANNEMANN ◽  
BERTOLD NÖCKEL ◽  
THOMAS LIPPERT ◽  
KLAUS SCHILLING
Keyword(s):  
The Other ◽  
Gradient Algorithm ◽  
Lattice Quantum Chromodynamics ◽  
Quark Masses ◽  
Fermion Operator ◽  
Lattice Fermion ◽  
Lattice Quantum ◽  
Minimal Residual Methods ◽  
Minimal Residual ◽  
Biconjugate Gradient

The stabilized biconjugate gradient algorithm BiCGStab recently presented by van der Vorst is applied to the inversion of the lattice fermion operator in the Wilson formulation of lattice Quantum Chromodynamics. Its computational efficiency is tested in a comparative study against the conjugate gradient and minimal residual methods. Both for quenched gauge configurations at β=6.0 and gauge configurations with dynamical fermions at β=5.4, we find BiCGStab to be superior to the other methods. BiCGStab turns out to be particularly useful in the chiral regime of small quark masses.

scholarly journals Evaluation of XcalableACC with tightly coupled accelerators/InfiniBand hybrid communication on accelerated cluster

2019 ◽  
Vol 33 (5) ◽  
pp. 869-884 ◽  
Author(s):  
Masahiro Nakao ◽  
Tetsuya Odajima ◽  
Hitoshi Murai ◽  
Akihiro Tabuchi ◽  
Norihisa Fujita ◽  
...  
Keyword(s):  
Programming Language ◽  
High Performance ◽  
Lattice Quantum Chromodynamics ◽  
Cluster Systems ◽  
Communication Latency ◽  
Lattice Quantum ◽  
Tightly Coupled ◽  
High Bandwidth ◽  
Sequential Code ◽  
Better Than

Accelerated clusters, which are cluster systems equipped with accelerators, are one of the most common systems in parallel computing. In order to exploit the performance of such systems, it is important to reduce communication latency between accelerator memories. In addition, there is also a need for a programming language that facilitates the maintenance of high performance by such systems. The goal of the present article is to evaluate XcalableACC (XACC), a parallel programming language, with tightly coupled accelerators/InfiniBand (TCAs/IB) hybrid communication on an accelerated cluster. TCA/IB hybrid communication is a combination of low-latency communication with TCA and high bandwidth with IB. The XACC language, which is a directive-based language for accelerated clusters, enables programmers to use TCA/IB hybrid communication with ease. In order to evaluate the performance of XACC with TCA/IB hybrid communication, we implemented the lattice quantum chromodynamics (LQCD) mini-application and evaluated the application on our accelerated cluster using up to 64 compute nodes. We also implemented the LQCD mini-application using a combination of CUDA and MPI (CUDA + MPI) and that of OpenACC and MPI (OpenACC + MPI) for comparison with XACC. Performance evaluation revealed that the performance of XACC with TCA/IB hybrid communication is 9% better than that of CUDA + MPI and 18% better than that of OpenACC + MPI. Furthermore, the performance of XACC was found to further increase by 7% by new expansion to XACC. Productivity evaluation revealed that XACC requires much less change from the serial LQCD code to implement the parallel LQCD code than CUDA + MPI and OpenACC + MPI. Moreover, since XACC can perform parallelization while maintaining the sequential code image, XACC is highly readable and shows excellent portability due to its directive-based approach.

Lattice QCD on GPU clusters, using the QUDA library and the Chroma software system

2012 ◽  
Vol 26 (4) ◽  
pp. 386-398 ◽  
Author(s):  
Bálint Joó ◽  
Mike A. Clark
Keyword(s):  
Quantum Chromodynamics ◽  
Graphics Processing Units ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Application Framework ◽  
Software System ◽  
Nuclear Forces ◽  
Lattice Quantum Chromodynamics ◽  
Lattice Quantum ◽  
Strong Scaling

The QUDA library for optimized lattice quantum chromodynamics using GPUs, combined with a high-level application framework such as the Chroma software system, provides a powerful tool for computing quark propagators, a key step in current calculations of hadron spectroscopy, nuclear structure, and nuclear forces. In this contribution we discuss our experiences, including performance and strong scaling of the QUDA library and Chroma on the Edge Cluster at Lawrence Livermore National Laboratory and on various clusters at Jefferson Lab. We highlight some scientific successes and consider future directions for graphics processing units in lattice quantum chromodynamics calculations.

scholarly journals Magnetic Moments of Light Nuclei from Lattice Quantum Chromodynamics

2014 ◽  
Vol 113 (25) ◽  
Author(s):  
S. R. Beane ◽  
E. Chang ◽  
S. Cohen ◽  
W. Detmold ◽  
H. W. Lin ◽  
...  
Keyword(s):  
Quantum Chromodynamics ◽  
Magnetic Moments ◽  
Light Nuclei ◽  
Lattice Quantum Chromodynamics ◽  
Lattice Quantum

scholarly journals Hadron resonance gas with van der Waals interactions

2020 ◽  
Vol 29 (05) ◽  
pp. 2040002 ◽  
Author(s):  
Volodymyr Vovchenko
Keyword(s):  
Equation Of State ◽  
Van Der Waals ◽  
Heavy Ion ◽  
Van Der Waals Interactions ◽  
Excluded Volume ◽  
Heavy Ion Collision ◽  
Lattice Quantum Chromodynamics ◽  
Qcd Critical Point ◽  
Lattice Quantum ◽  
Ion Collision

An overview of a hadron resonance gas (HRG) model that includes van der Waals (vdW) interactions between hadrons is presented. Applications of the excluded volume HRG model to heavy-ion collision data and lattice quantum chromodynamics (QCD) equation of state are discussed. A recently developed quantum vdW HRG model is covered as well. Applications of this model in the context of the QCD critical point are elaborated.

scholarly journals Baryon-baryon interactions and spin-flavor symmetry from lattice quantum chromodynamics

2017 ◽  
Vol 96 (11) ◽  
Author(s):  
Michael L. Wagman ◽  
Frank Winter ◽  
Emmanuel Chang ◽  
Zohreh Davoudi ◽  
William Detmold ◽  
...  
Keyword(s):  
Quantum Chromodynamics ◽  
Flavor Symmetry ◽  
Lattice Quantum Chromodynamics ◽  
Lattice Quantum

scholarly journals THE ELECTROMAGNETIC FORM FACTOR OF THE PION: RESULTS FROM THE LATTICE

2013 ◽  
Vol 22 (12) ◽  
pp. 1330030 ◽  
Author(s):  
BASTIAN B. BRANDT
Keyword(s):  
Form Factor ◽  
Quantum Chromodynamics ◽  
Quality Criteria ◽  
Vector Form ◽  
Physical Point ◽  
Lattice Quantum Chromodynamics ◽  
Lattice Quantum ◽  
Future Challenges ◽  
Recent Developments ◽  
Systematic Effects

This review contains an overview over recent results for the electromagnetic iso-vector form factor of the pion obtained in lattice quantum chromodynamics (QCD) with dynamical fermions. Particular attention is given to the extrapolation to the physical point and an easy assessment of the control over the main systematic effects by imposing quality criteria and an associated sign code, similar to the ones used by the FLAG working group. Also included is a brief discussion of recent developments and future challenges concerning the accurate extraction of the form factor in the lattice framework.

scholarly journals DETERMINATION OF LIGHT QUARK MASSES IN QCD

2010 ◽  
Vol 25 (29) ◽  
pp. 5223-5234 ◽  
Author(s):  
C. A. DOMINGUEZ
Keyword(s):  
Strange Quark ◽  
Sum Rules ◽  
Standard Procedure ◽  
Light Quark ◽  
Qcd Sum Rules ◽  
Quark Masses ◽  
Systematic Uncertainties ◽  
Better Than ◽  
The Ideal

The standard procedure to determine (analytically) the values of the quark masses is to relate QCD two-point functions to experimental data in the framework of QCD sum rules. In the case of the light quark sector, the ideal Green function is the pseudoscalar correlator which involves the quark masses as an overall multiplicative factor. For the past thirty years this method has been affected by systematic uncertainties originating in the hadronic resonance sector, thus limiting the accuracy of the results. Recently, a major breakthrough has been made allowing for a considerable reduction of these systematic uncertainties and leading to light quark masses accurate to better than 8%. This procedure will be described in this talk for the up-, down-, strange-quark masses, after a general introduction to the method of QCD sum rules.

scholarly journals Lattice QCD input for nuclear structure and reactions

2018 ◽  
Vol 175 ◽  
pp. 01022 ◽  
Author(s):  
Zohreh Davoudi
Keyword(s):  
Quantum Chromodynamics ◽  
Nuclear Reactions ◽  
Many Body ◽  
Quark Masses ◽  
The Past ◽  
Lattice Quantum ◽  
Nuclear Systems ◽  
Community Effort ◽  
The Impact ◽  
Made In

Explorations of the properties of light nuclear systems beyond their lowestlying spectra have begun with Lattice Quantum Chromodynamics. While progress has been made in the past year in pursuing calculations with physical quark masses, studies of the simplest nuclear matrix elements and nuclear reactions at heavier quark masses have been conducted, and several interesting results have been obtained. A community effort has been devoted to investigate the impact of such Quantum Chromodynamics input on the nuclear many-body calculations. Systems involving hyperons and their interactions have been the focus of intense investigations in the field, with new results and deeper insights emerging. While the validity of some of the previous multi-nucleon studies has been questioned during the past year, controversy remains as whether such concerns are relevant to a given result. In an effort to summarize the newest developments in the field, this talk will touch on most of these topics.

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