Resummation of large endpoint corrections to color-octet J/ψ photoproduction

Sean Fleming, Adam K. Leibovich, Thomas Mehen

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Abstract

An unresolved problem in J/ψ phenomenology is a systematic understanding of the differential photoproduction cross section, dσ/dz[γ+p→J/ψ+X], where z=Eψ/Eγ in the proton rest frame. In the nonrelativistic QCD (NRQCD) factorization formalism, fixed-order perturbative calculations of color-octet mechanisms suffer from large perturbative and nonperturbative corrections that grow rapidly in the endpoint region, z→1. In this paper, NRQCD and soft collinear effective theory are combined to resum these large corrections to the color-octet photoproduction cross section. We derive a factorization theorem for the endpoint differential cross section involving the parton distribution function and the color-octet J/ψ shape functions. A one-loop matching calculation explicitly confirms our factorization theorem at next-to-leading order. Large perturbative corrections are resummed using the renormalization group. The calculation of the color-octet contribution to dσ/dz is in qualitative agreement with data. Quantitative tests of the universality of color-octet matrix elements require improved knowledge of shape functions entering these calculations as well as resummation of the color-singlet contribution which accounts for much of the total cross section and also peaks near the endpoint.

Original languageEnglish (US)
Article number114004
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume74
Issue number11
DOIs
StatePublished - Dec 14 2006

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ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

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