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arXiv · 1303.3234

Radiative improvement of the lattice NRQCD action using the background field method with applications to quarkonium spectroscopy

T. C. Hammant·A. G. Hart·G. M. von Hippel·R. R. Horgan·C. J. Monahan
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Abstract

We apply the background field (BF) method to Non-Relativistic QCD (NRQCD) on the lattice in order to determine the one-loop radiative corrections to the coefficients of the NRQCD action in a manifestly gauge-covariant manner by matching the NRQCD prediction for particular on-shell processes with those of relativistic continuum QCD. We explain how the BF method is implemented in automated perturbation theory and discuss the technique for matching the relativistic and non-relativistic theories. We compute the one-loop radiative corrections to the sigma.B and Darwin terms for the NRQCD action currently used in simulations, as well as the one-loop coefficients of the spin-dependent O(alpha^2) four-fermion contact terms. The effect of the corrections on the hyperfine splitting of bottomonium is estimated using earlier simulation results; the corrected lattice prediction is found to be in agreement with experiment. Agreement of the hyperfine splitting of bottomonium and the B-meson system is confirmed by recent simulation studies (Dowdall et al.) which include our NRQCD radiative corrections for the first time.

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T. C. Hammant, A. G. Hart, G. M. von Hippel, R. R. Horgan, C. J. Monahan. 2015-11-16. Radiative improvement of the lattice NRQCD action using the background field method with applications to quarkonium spectroscopy. https://doi.org/10.1103/physrevd.88.014505

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