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arXiv · hep-ph/0407259

Flavor-singlet light-cone amplitudes and radiative Upsilon decays in SCET

Sean Fleming·Adam K. Leibovich
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Abstract

We study the evolution of flavor-singlet, light-cone amplitudes in the soft-collinear effective theory (SCET), and reproduce results previously obtained by a different approach. We apply our calculation to the color-singlet contribution to the photon endpoint in radiative Upsilon decay. In a previous paper, we studied the color-singlet contributions to the endpoint, but neglected operator mixing, arguing that it should be a numerically small effect. Nevertheless the mixing needs to be included in a consistent calculation, and we do just that in this work. We find that the effects of mixing are indeed numerically small. This result combined with previous work on the color-octet contribution and the photon fragmentation contribution provides a consistent theoretical treatment of the photon spectrum in radiative Upsilon decay.

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Sean Fleming, Adam K. Leibovich. 2004-07-22. Flavor-singlet light-cone amplitudes and radiative Upsilon decays in SCET. https://doi.org/10.1103/physrevd.70.094016

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