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We present a new multigrid solver that is suitable for the Dirac operator in the presence of disordered gauge fields. The key behind the success of the algorithm is an adaptive projection onto the coarse grids that preserves the near null…

High Energy Physics - Lattice · Physics 2008-11-26 J. Brannick , R. C. Brower , M. A. Clark , J. C. Osborn , C. Rebbi

We present promising initial results of our adaptive multigrid solver developed for application directly to the non-Hermitian Wilson-Dirac system in 4 dimensions, as opposed to the solver developed in [1] for the corresponding normal…

High Energy Physics - Lattice · Physics 2010-04-05 M. A. Clark , J. Brannick , R. C. Brower , S. F. McCormick , T. A. Manteuffel , J. C. Osborn , C. Rebbi

We present a new multigrid solver that is suitable for the Dirac operator in the presence of disordered gauge fields. The key behind the success of the algorithm is an adaptive projection onto the coarse grids that preserves the near null…

High Energy Physics - Lattice · Physics 2008-11-26 J. Brannick , R. C. Brower , M. A. Clark , J. C. Osborn , C. Rebbi

We describe an adaptive multigrid algorithm for solving inverses of the domain-wall fermion operator. Our multigrid algorithm uses an adaptive projection of near-null vectors of the domain-wall operator onto coarser four-dimensional…

High Energy Physics - Lattice · Physics 2012-05-15 Saul D. Cohen , R. C. Brower , M. A. Clark , J. C. Osborn

We report on the first successful QCD multigrid algorithm which demonstrates constant convergence rates independent of quark mass and lattice volume for the Wilson Dirac operator. The new ingredient is the adaptive method for constructing…

High Energy Physics - Lattice · Physics 2010-04-15 Ronald Babich , James Brannick , Richard C. Brower , Michael A. Clark , Saul D. Cohen , James C. Osborn , Claudio Rebbi

In lattice QCD computations a substantial amount of work is spent in solving discretized versions of the Dirac equation. Conventional Krylov solvers show critical slowing down for large system sizes and physically interesting parameter…

High Energy Physics - Lattice · Physics 2014-04-29 Andreas Frommer , Karsten Kahl , Stefan Krieg , Björn Leder , Matthias Rottmann

We present a multigrid based eigensolver for computing low-modes of the Hermitian Wilson Dirac operator. For the non-Hermitian case multigrid methods have already replaced conventional Krylov subspace solvers in many lattice QCD…

High Energy Physics - Lattice · Physics 2015-09-24 Gunnar Bali , Sara Collins , Andreas Frommer , Karsten Kahl , Issaku Kanamori , Benjamin Müller , Matthias Rottmann , Jakob Simeth

Eigenvalues of the Hermitian Wilson-Dirac operator are of special interest in several lattice QCD simulations, e.g., for noise reduction when evaluating all-to-all propagators. In this paper we present a Davidson-type eigensolver that…

High Energy Physics - Lattice · Physics 2020-10-28 Andreas Frommer , Karsten Kahl , Francesco Knechtli , Matthias Rottmann , Artur Strebel , Ian Zwaan

Critical slowing down for the Krylov Dirac solver presents a major obstacle to further advances in lattice field theory as it approaches the continuum solution. We propose a new multi-grid approach for chiral fermions, applicable to both…

High Energy Physics - Lattice · Physics 2020-12-30 Richard C. Brower , M. A. Clark , Dean Howarth , Evan S. Weinberg

In QCD chiral symmetry is explicitly broken by quark masses, the effect of which can be described reliably by chiral perturbation theory. Effects of explicit chiral symmetry breaking by the lattice regularisation of the Dirac operator,…

High Energy Physics - Lattice · Physics 2011-01-27 Nigel Cundy , Tony Kennedy , Andreas Schäfer

The overlap operator is a lattice discretization of the Dirac operator of quantum chromodynamics, the fundamental physical theory of the strong interaction between the quarks. As opposed to other discretizations it preserves the important…

High Energy Physics - Lattice · Physics 2014-10-28 James Brannick , Andreas Frommer , Karsten Kahl , Björn Leder , Matthias Rottmann , Artur Strebel

We present a modification to the setup algorithm for the multigrid preconditioner of Wilson fermions in lattice QCD. A larger number of test vectors than that used in conventional multigrid is generated by the smoother. This set of test…

High Energy Physics - Lattice · Physics 2025-02-06 Travis Whyte , Andreas Stathopoulos , Eloy Romero

A modification to the setup algorithm for the multigrid preconditioner of Wilson fermions in lattice QCD is presented. A larger basis of test vectors than that used in conventional multigrid is calculated by the smoother and truncated by…

High Energy Physics - Lattice · Physics 2025-05-21 Travis Whyte , Andreas Stathopoulos , Eloy Romero

Adaptive multi-grid methods have proven very successful in dealing with critical slow down for the Wilson-Dirac solver in lattice gauge theory. Multi-grid algorithms developed for Staggered fermions using the K\"ahler-Dirac…

High Energy Physics - Lattice · Physics 2023-04-28 Venkitesh Ayyar , Richard Brower , M. A. Clark , Mathias Wagner , Evan Weinberg

In lattice QCD computations a substantial amount of work is spent in solving linear systems arising in Wilson's discretization of the Dirac equations. We show first numerical results of the extension of the two-level DD-\alpha AMG method to…

High Energy Physics - Lattice · Physics 2013-07-24 A. Frommer , K. Kahl , S. Krieg , B. Leder , M. Rottmann

In this paper we discuss how the peculiar properties of twisted lattice QCD at maximal twist can be employed to set up a consistent computational scheme in which, despite the explicit breaking of chiral symmetry induced by the presence of…

High Energy Physics - Lattice · Physics 2010-02-03 R. Frezzotti , G. C. Rossi

We develop an algebraic multigrid method for solving the non-Hermitian Wilson discretization of the 2-dimensional Dirac equation. The proposed approach uses a bootstrap setup algorithm based on a multigrid eigensolver. It computes test…

Numerical Analysis · Mathematics 2013-08-29 James Brannick , Karsten Kahl

The Overlap-Dirac operator provides a lattice regularization of massless vector gauge theories with an exact chiral symmetry. Practical implementations of this operator and recent results in quenched QCD using this Overlap-Dirac operator…

High Energy Physics - Lattice · Physics 2007-05-23 Robert G. Edwards , Urs M. Heller , Rajamani Narayanan

It is possible to improve the chiral behaviour and the approach to the continuum limit of correlation functions in lattice QCD with standard and twisted Wilson fermions by taking arithmetic averages of correlators computed in theories…

High Energy Physics - Lattice · Physics 2009-11-10 R. Frezzotti , G. C. Rossi

We present an adaptive multigrid Dirac solver developed for Wilson clover fermions which offers order-of-magnitude reductions in solution time compared to conventional Krylov solvers. The solver incorporates even-odd preconditioning and…

High Energy Physics - Lattice · Physics 2011-05-25 J. C. Osborn , R. Babich , J. Brannick , R. C. Brower , M. A. Clark , S. D. Cohen , C. Rebbi
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