%0 Journal Article
%A Eicker, N.
%A Glässner, U.
%A Güsken, S.
%A Hoeber, H.
%A Lippert, T.
%A Ritzenhöfer, G.
%A Schilling, K.
%A Siegert, G.
%A Spitz, A.
%A Ueberholz, P.
%A Viehoff, J.
%T Evaluating sea quark contributions to flavour-singlet operators in lattice QCD
%J Physics letters / B B
%V 389
%N 4
%@ 0370-2693
%C Amsterdam
%I North-Holland Publ.
%M FZJ-2019-01116
%P 720 - 726
%D 1996
%X In a full QCD lattice study with Nf = 2 Wilson fermions, we seek to optimize the signals for the disconnected contributions to the matrix element of flavour-singlet operators between nucleon states, which are indicative for sea quark effects. We demonstrate, in form of a fluctuation analysis to the noisy estimator technique, that — in order to achieve a tolerable signal to noise-ratio in full QCD — it is advantageous to work with a Z2-noise source rather than to rely only on gauge invariance to cancel non-gauge-invariant background. In the case of the πNσ-term, we find that 10 Z2-noise sources suffice on our sample (about 150 independent QCD configurations at β = 5.6 on 163 × 32 withκsea = 0.157, equivalent to Mπ/Mϱ = 0.76 (1), to achieve decent signals and adequate fluctuations, rather than 300 such sources as recently used in quenched simulations.
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1016/S0370-2693(96)80015-3
%U https://juser.fz-juelich.de/record/860341