Radiative improvement of the lattice NRQCD action using the background field method and application to the hyperfine splitting of quarkonium states

摘要

We present the first application of the background field method toNon-Relativistic QCD (NRQCD) on the lattice in order to determine the one-loopradiative corrections to the coefficients of the NRQCD action in a manifestlygauge-covariant manner. The coefficient of the $\sigma\cdot B$ term in theNRQCD action is computed at the one-loop level; the resulting shift of thehyperfine splitting of bottomonium is found to bring the lattice predictions inline with experiment.