Disconnected Quark Loop Contributions to Nucleon Structure

We calculate the disconnected contribution to isoscalar nucleon charges for scalar, axial and tensor channels of light and strange quarks. The calculation has been done with the Clover valence quarks on the MILC N_f = 2+1+1 HISQ lattices whose light quark masses corresponding to the pion masses of 305MeV and 217MeV at a ≈ 0:12fm and 312MeV at a ≈ 0:09fm. All-modeaveraging technique is used for the evaluation two-point functions. Disconnected quark loops are estimated by using the truncated solver method with Gaussian random noise sources. Contamination from the excited states is removed by fitting the results of various source-sink separations and operator insertions to the formula including up to the first excited state, simultaneously.