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

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• 作者：Georg von Hippel^a ; ^{hippel@uni-mainz.de} ; Thomas D. Rae^b ; Eigo Shintani^a ; ^c ; Hartmut Wittig^a ; ^d
• 刊名：Nuclear Physics B
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：914
• 期：Complete
• 页码：138-159
• 全文大小：1092 K
• 卷排序：914

文摘

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 Nf=2Nf=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 ts∼1.5 fmts∼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 ts∼1.2 fmts∼1.2 fm, whereas the excited-state contamination in the scalar and tensor charges seems to be small.