2006/07/11 by Sean Fleming, Adam K. Leibovich, Thomas Mehen · 3 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1103/physrevd.74.114004
published as Phys.Rev.D74:114004,2006 · 30 pages, 6 figures
arxiv created 2006/07/11 · openalex publication_date 2006/12/08 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
An unresolved problem in J/\ensuremathψ phenomenology is a systematic understanding of the differential photoproduction cross section, d\ensuremathσ/dz[\ensuremathγ+p\ensuremath→J/\ensuremathψ+X], where z=E_\ensuremathψ/E_\ensuremathγ 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\ensuremath→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/\ensuremathψ 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 d\ensuremathσ/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.