The renormalised O(a) improved vector current in three-flavour lattice QCD with Wilson quarks

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2021-03, Vol.81 (3)
• Main Authors: Heitger, Jochen, Joswig, Fabian
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics and Cosmology; Coefficients; Elementary Particles; Flavor (particle physics); Hadrons; Heavy Ions; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Physics; Physics and Astronomy; Quantum chromodynamics; Quantum Field Theories; Quantum Field Theory; Quarks; Regular Article – Theoretical Physics; String Theory; Vector currents
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-021-09037-4

We present the results of a non-perturbative determination of the improvement coefficient c V and the renormalisation factor Z V , which define the renormalised vector current in three-flavour O ( a ) improved lattice QCD with Wilson quarks and tree-level Symanzik-improved gauge action. In case of the improvement coefficient, we consider both lattice descriptions of the vector current, the local as well as the conserved (i.e., point-split) one. Our improvement and normalisation conditions are based on massive chiral Ward identities and numerically evaluated in the Schrödinger functional setup, which allows to eliminate finite quark mass effects in a controlled way. In order to ensure a smooth dependence of the renormalisation constant and improvement coefficients on the bare gauge coupling, our computation proceeds along a line of constant physics, covering the typical range of lattice spacings 0.04 fm ≲ a ≲ 0.1 fm that is useful for phenomenological applications. Especially for the improvement coefficient of the local vector current, we report significant differences between the one-loop perturbative estimates and our non-perturbative results.