  Analyses on possible systematics in some isovector nucleon observables in the
RBC+UKQCD 2+1-flavor dynamical domain-wall fermion (DWF) lattice-QCD are
presented. The vector charge, axial charge, quark momentum and helicity
fractions, and transversity are discussed using mainly the
Iwasaki\(\times\)DSDR ensemble at pion mass of 170 MeV. No autocorrelation
issue is observed in the vector charge and quark momentum and helicity
fractions. Blocked Jack-knife analyses expose significant growth of estimated
error for the axial charge with increasing block sizes that are similar to or
larger than the known autocorrelation time of the gauge-field topological
charge. Similar growth is seen in the transversity. These two observables,
however, do not seem correlated with the topological charge.
