THE PION-NUCLEON SIGMA-TERM WITH DYNAMICAL WILSON FERMIONS - A FEASIBILITY STUDY

In a full QCD lattice study with N-f = 2 Wilson fermions, we seek to o ptimize the signals for the disconnected contributions to the Pion Nuc leon Sigma term sigma(N). We demonstrate, in form of a numerical analy sis, that in order to achieve a tolerable signal to noise-ratio in ful l QCD - it is advantageous to work with a Z(2)-noise source rather tha n to use Gaussian noise sources or to rely only on gauge invariance to cancel non-gauge-invariant background. We find that 10 Z(2)-noise sou rces suffice on our sample (about 150 independent QCD configurations a t beta = 5.6 on 16(3) x 32 with kappa(sea) = 0.157, equivalent to M(pi )/M(rho) = 0.76(1)), to achieve decent signals and adequate fluctuatio ns, rather than 300 such sources as recently used in quenched simulati ons.