Speaker
Description
We report a new high precision calculation of the isospin vector charge $g_{S,T}$ of the nucleon using recently proposed ``blending" method which provides a high-accuracy stochastic estimate of the all-to-all fermion propagator. By combining the current-inspired interpolation field, which can efficiently cancel the major excited state contamination, we found that both $g_{S}$ and $g_T$ have significant finite volume effects which are not suppressed in the chiral limit. Using 15 of the $N_f=2+1$ lattice ensembles which covers 5 lattice spacing, 5 combinations with the same quark masses and lattice spacing but multiple volumes, and includes three at the physical pion mass, we report so far most accurate lattice QCD prediction $g_T^{\rm QCD} = 1.0253[94]_{\rm tot}(55)_{\rm stat} (46)_{a} (59)_{\rm FV} (13)_\chi (06)_{\rm ex}$ and $g_S^{\rm QCD} = 1.103[44]_{\rm tot}(32)_{\rm stat} ( 04)_{a} (26)_{\rm FV} (01)_\chi (15)_{\rm ex}$ at $\overline{\mathrm{MS}}$ 2~GeV, with the systematic uncertainty from infinite volume, continuum, and chiral extrapolations.
