Nucleon matrix elements from lattice QCD with all-mode-averaging and a domain-decomposed solver: an exploratory study

We study the performance of all-mode-averaging (AMA) when used in conjunction with a locally deflated SAP-preconditioned solver, determining how to optimize the local block sizes and number of deflation fields in order to minimize the computational cost for a given level of overall statistical accur...

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Bibliographic Details
Published in:arXiv.org 2016-11
Main Authors: Georg von Hippel, Rae, Thomas D, Shintani, Eigo, Wittig, Hartmut
Format: Article
Language:English
Subjects:
Contamination
Mathematical analysis
Quantum chromodynamics
Tensors
Online Access:Get full text
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Summary:We study the performance of all-mode-averaging (AMA) when used in conjunction with a locally deflated SAP-preconditioned solver, determining how to optimize the local block sizes and number of deflation fields in order to minimize the computational cost for a given level of overall statistical accuracy. We find that AMA enables a reduction of the statistical error on nucleon charges by a factor of around two at the same cost when compared to the standard method. As a demonstration, we compute the axial, scalar and tensor charges of the nucleon in \(N_f=2\) lattice QCD with non-perturbatively O(a)-improved Wilson quarks, using O(10,000) measurements to pursue the signal out to source-sink separations of \(t_s\sim 1.5\) fm. Our results suggest that the axial charge is suffering from a significant amount (5-10%) of excited-state contamination at source-sink separations of up to \(t_s\sim 1.2\) fm, whereas the excited-state contamination in the scalar and tensor charges seems to be small.
ISSN:2331-8422
DOI:10.48550/arxiv.1605.00564