2008/04/02 by J. A. Oller, L. Roca
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph #nucl-th
paper · pdf · doi:10.1140/epja/i2008-10600-0
published as Eur.Phys.J.A37:15-32,2008 · 31 pages, 9 figures
arxiv created 2008/04/02 · openalex publication_date 2008/06/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We perform a theoretical study based on dispersion relations of the reaction γγ→ π0π0 emphasizing the low energy region. We discuss how the f0(980) signal emerges in γγ→ ππwithin the dispersive approach and how this fixes to a large extent the phase of the isoscalar S-wave γγ→ ππamplitude above the KK threshold. This allows us to make sharper predictions for the cross section at lower energies and our results could then be used to distinguish between different ππisoscalar S-wave parameterizations with the advent of new precise data on γγ→π0π0. We compare our dispersive approach with an updated calculation employing Unitary Chiral Perturbation Theory (U\chiPT). We also pay special attention to the role played by the σresonance in γγ→ππand calculate its coupling and width to gammaγ, for which we obtain Γ(σ→γγ)=(1.68± 0.15) KeV.