Non-perturbative renormalization of the QCD flavour-singlet local vector current

Abstract

We compute non-perturbatively the renormalization constant of the flavour-singlet local vector current $Z_V$ in lattice QCD with 3 massless flavours. Gluons are discretized by the Wilson plaquette action while quarks by the O($a$)-improved Wilson--Dirac operator. The constant $Z_V$ is fixed by comparing the expectation values (1-point functions) of the conserved and local vector currents at finite temperature in the presence of shifted boundary conditions and at non-zero imaginary chemical potential. Monte Carlo simulations with a moderate computational cost allow us to obtain $Z_V$ with an accuracy of about 8\textperthousand\, for values of the inverse bare coupling constant $\beta =6/g_0^2$ in the range $5.3\le \beta \le 11.5$.

Comments: 7 pages, 4 figures, minor changes