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Type: Journal article
Title: Variational approach to the calculation of gA
Other Titles: Variational approach to the calculation of g(A)
Author: Owen, B.
Dragos, J.
Kamleh, W.
Leinweber, D.
Mahbub, M.
Menadue, B.
Zanotti, J.
Citation: Physics Letters B, 2013; 723(1-3):217-223
Publisher: Elsevier Science BV
Issue Date: 2013
ISSN: 0370-2693
Statement of
Benjamin J. Owen, Jack Dragos, Waseem Kamleh, Derek B. Leinweber, M. Selim Mahbub, Benjamin J. Menadue, James M. Zanotti
Abstract: A long standing problem in lattice QCD has been the discrepancy between the experimental and calculated values for the axial charge of the nucleon, g(A)≡G(A)(Q2=0)gA≡GA(Q²=0). Though finite volume effects have been shown to be large, it has also been suggested that excited state effects may also play a significant role in suppressing the value of g(A). In this work, we apply a variational method to generate operators that couple predominantly to the ground state, thus systematically removing excited state contamination from the extraction of g(A). The utility and success of this approach is manifest in the early onset of ground state saturation and the early onset of a clear plateau in the correlation function ratio proportional to g(A). Through a comparison with results obtained via traditional methods, we show how excited state effects can suppress g(A) by as much as 8% if sources are not properly tuned or source–sink separations are insufficiently large.
Keywords: Lattice QCD; Nucleon axial charge; Variational method
Rights: Crown copyright © 2013yD
RMID: 0020128835
DOI: 10.1016/j.physletb.2013.04.063
Appears in Collections:Chemistry and Physics publications

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