2004/04/30 by Ron-Chou Hsieh, Hsiang-nan Li
Physics and Astronomy · #Factorization #High-Energy Particle Collisions Research #Meson #Particle physics #Particle physics theoretical and experimental studies #Perturbative QCD #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #State (computer science) #hep-ph
paper · pdf · doi:10.1103/physrevd.70.056002
published as Phys.Rev. D70 (2004) 056002 · 9 pages, 2 figures
arxiv created 2004/07/01 · openalex publication_date 2004/09/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We propose that the different angular distributions in two-photon collisions observed at low and high center-of-mass energies W_\ensuremathγ\ensuremathγ indicate the transition from nonperturbative to perturbative QCD. We calculate the differential cross sections of \ensuremathγ\ensuremathγ\ensuremath→\ensuremathπ\ensuremathπ,KK in the angle \ensuremathθ of one of the final-state mesons using QCD sum rules and the perturbative QCD approach based on kT factorization theorem. Our predictions from sum rules (perturbative QCD) decrease (increase) with |cos\ensuremathθ|, consistent with the Belle data of \ensuremathγ\ensuremathγ\ensuremath→K+K^\ensuremath- for W_\ensuremathγ\ensuremathγ\ensuremath≈1.5\ensuremath-1.7(2.2\ensuremath-2.4) GeV.