1997/08/13 by Stanley J. Brodsky, S. J. Brodsky, Brodsky, S. J.
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Pulsars and Gravitational Waves Research #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/9708345
LaTex, 15 pages
arxiv created 1997/08/13 · openalex publication_date 1997/08/13 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Exclusive γγ→ hadron pairs are among the most fundamental processes in QCD, providing a detailed examination of Compton scattering in the crossed channel. In the high momentum transfer domain (s,t, large,θcm for t/s fixed), these processes can be computed from first principles in QCD, yielding important information on the nature of the QCD coupling αs and the form of hadron distribution amplitudes. Similarly, the transition form factors γ^*γ, γ^*γ→ π0, η0,η^′,ηc ... provide rigorous tests of QCD and definitive determinations of the meson distribution amplitudes ϕH(x,Q). We show that the assumption of a frozen coupling at low momentum transfers can explain the observed scaling of two-photon exclusive processes.