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J/psi Photo-production at Large z in Soft Collinear Effective Theory

Sean Fleming·Adam K. Leibovich·Thomas Mehen
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Abstract

One of the outstanding problems in J/ψphysics is a systematic understanding of the differential photo-production cross section dsigma/dz(gamma + p -> J/psi + X), where z= E_psi/E_gamma in the proton rest frame. The theoretical prediction based on the non-relativistic QCD (NRQCD) factorization formalism has a color-octet contribution which grows rapidly in the endpoint region, z -> 1, spoiling perturbation theory. In addition there are subleading operators which are enhanced by powers of 1/(1-z) and they must be resummed to all orders. Here an update of a systematic analysis is presented. The approach used to organize the endpoint behavior of the photo-production cross section is based on a combination of NRQCD and soft collinear effective theory. While a final result is not yet available, an intermediate result indicates that better agreement between theory and data will be achieved in this framework.

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Sean Fleming, Adam K. Leibovich, Thomas Mehen. 2005-12-15. J/psi Photo-production at Large z in Soft Collinear Effective Theory. https://doi.org/10.1142/9789812773524_0022

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