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arXiv · hep-lat/0107011

Bottomonium Decay Matrix Elements from Lattice QCD with Two Light Quarks

G. T. Bodwin·D. K. Sinclair·S. Kim
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Abstract

We calculate the long-distance matrix elements for the decays of the Upsilon (eta_b) and chi_b (h_b) states in lattice QCD with two flavors of light dynamical quarks. We relate the lattice matrix elements to their continuum counterparts through one-loop order in perturbation theory. In the case of the leading S-wave matrix element, we compare our result with a phenomenological value that we extract from the experimental leptonic decay rate by using the theoretical expression for the decay rate, accurate through relative order alpha_s. Whereas estimates of the leading S-wave matrix element from quenched QCD are 40--45% lower than the phenomenological value, the two-flavor estimate of the same matrix element is close to the phenomenological value. Extrapolating to the real world of 2+1 light flavors, we find that this matrix element is approximately 6% higher than the phenomenological value, but that the phenomenological value lies within our error bars. We also compute the color-singlet and color-octet matrix elements for P-wave decays. We find the value of the color-singlet matrix element for 2+1 flavors to be approximately 70% larger than the quenched value and the value of the color-octet matrix element for 2+1 flavors to be approximately 40% larger than the quenched value.

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BibTeXRIS

G. T. Bodwin, D. K. Sinclair, S. Kim. 2002-01-10. Bottomonium Decay Matrix Elements from Lattice QCD with Two Light Quarks. https://doi.org/10.1103/physrevd.65.054504

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