TY  - JOUR
AU  - Eicker, N.
AU  - Glässner, U.
AU  - Güsken, S.
AU  - Hoeber, H.
AU  - Lippert, T.
AU  - Ritzenhöfer, G.
AU  - Schilling, K.
AU  - Siegert, G.
AU  - Spitz, A.
AU  - Ueberholz, P.
AU  - Viehoff, J.
TI  - Evaluating sea quark contributions to flavour-singlet operators in lattice QCD
JO  - Physics letters / B B
VL  - 389
IS  - 4
SN  - 0370-2693
CY  - Amsterdam
PB  - North-Holland Publ.
M1  - FZJ-2019-01116
SP  - 720 - 726
PY  - 1996
AB  - 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.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1016/S0370-2693(96)80015-3
UR  - https://juser.fz-juelich.de/record/860341
ER  -