Nonsinglet vector current in lattice QCD: O ( a ) -improvement from large volumes

In previous work, we determined the improvement coefficients c V and c V ˜ required for the massless O ( a ) -improvement of the local and point-split discretizations of the nonsinglet vector current for N f = 3 nonperturbatively O ( a ) -improved Wilson fermions and the Lüscher-Weisz gauge action, using ensembles of large-volume configurations generated by the coordinated lattice simulations (CLS) initiative. A new estimate for the mass-dependent improvement coefficient b ¯ A eff has recently become available, differing from the one used in our earlier study, and on which our implementation via a massive axial Ward identity relied. Here, we update our analysis of the mass-independent vector improvement coefficients based on the new axial current improvement coefficient, and analyze additional ensembles with a different chiral trajectory in order to validate our results at two values of the bare coupling. We find that using the new estimate of b ¯ A eff improves the consistency between the two chiral trajectories, as well as with a previous determination of the improvement coefficients directly in the massless limit on small volumes.