21 research outputs found
Spin on the lattice
I review the current status of hadronic structure computations on the
lattice. I describe the basic lattice techniques and difficulties and present
some of the latest lattice results; in particular recent results of the RBC
group using domain wall fermions are also discussed.Comment: 10 pages, 10 figures, plenary talk given at SPIN2002, BNL, updated
references, corrected typo
Nuclear Physics from Lattice QCD
This is the final report for this project
Computing and deflating eigenvalues while solving multiple right hand side linear systems in Quantum Chromodynamics
We present a new algorithm that computes eigenvalues and eigenvectors of a
Hermitian positive definite matrix while solving a linear system of equations
with Conjugate Gradient (CG). Traditionally, all the CG iteration vectors could
be saved and recombined through the eigenvectors of the tridiagonal projection
matrix, which is equivalent theoretically to unrestarted Lanczos. Our algorithm
capitalizes on the iteration vectors produced by CG to update only a small
window of vectors that approximate the eigenvectors. While this window is
restarted in a locally optimal way, the CG algorithm for the linear system is
unaffected. Yet, in all our experiments, this small window converges to the
required eigenvectors at a rate identical to unrestarted Lanczos. After the
solution of the linear system, eigenvectors that have not accurately converged
can be improved in an incremental fashion by solving additional linear systems.
In this case, eigenvectors identified in earlier systems can be used to
deflate, and thus accelerate, the convergence of subsequent systems. We have
used this algorithm with excellent results in lattice QCD applications, where
hundreds of right hand sides may be needed. Specifically, about 70 eigenvectors
are obtained to full accuracy after solving 24 right hand sides. Deflating
these from the large number of subsequent right hand sides removes the dreaded
critical slowdown, where the conditioning of the matrix increases as the quark
mass reaches a critical value. Our experiments show almost a constant number of
iterations for our method, regardless of quark mass, and speedups of 8 over
original CG for light quark masses.Comment: 22 pages, 26 eps figure
First Calculation of Hyperon Axial Couplings from Lattice QCD
In this work, we report the first lattice calculation of hyperon axial
couplings, using the 2+1-flavor MILC configurations and domain-wall fermion
valence quarks. Both the and axial couplings are computed for
the first time in lattice QCD. In particular we find that and .Comment: 5 pages, 2 figure
Lattice QCD and Particle Physics
Contribution from the USQCD Collaboration to the Proceedings of the US
Community Study on the Future of Particle Physics (Snowmass 2021).Comment: 27 pp. main text, 4 pp. appendices, 30 pp. reference
Lattice QCD and Particle Physics
Contribution from the USQCD Collaboration to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021)