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arXiv · hep-lat/9706003

Upsilon Spectrum from NRQCD with Improved Action

UKQCD Collaboration·T. Manke·I. T. Drummond·R. R. Horgan·H. P. Shanahan
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Abstract

We explore the effect of higher order operators in the non-relativistic formulation of QCD (NRQCD). We calculated masses in the b \bar b spectrum using quenched gauge configurations at beta = 6.0 and two different NRQCD actions which have been corrected to order mv^4 and mv^6. The two-point functions are calculated in a gauge invariant fashion. We find the general structure of the spectrum to be the same in the two cases. Using the P - 3S1 splitting we determine the inverse lattice spacings to be 2.44(4) GeV and 2.44(5) GeV for the mv^4 and mv^6 actions, respectively. We do observe shifts in the spin splittings. The hyperfine splitting is reduced by approximately 4 MeV, while the fine splitting is down by up to 10 MeV, albeit with large statistical errors.

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UKQCD Collaboration, T. Manke, I. T. Drummond, R. R. Horgan, H. P. Shanahan. 1997-06-04. Upsilon Spectrum from NRQCD with Improved Action. https://doi.org/10.1016/s0370-2693(97)00813-7

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