{"paper":{"title":"The Reaction $\\gamma\\gamma\\to\\pi^0\\pi^0$ in Generalized Chiral Perturbation Theory","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"B. Moussallam, J. Stern, M. Knecht","submitted_at":"1994-02-18T13:43:10Z","abstract_excerpt":"The cross section for $\\gamma\\gamma\\to\\pi^0\\pi^0$ and the pion polarizabilities are computed, within generalized chiral perturbation theory, in the full one loop approximation, {\\it i.e.} up to and including order $O({p^5})$. The result depends on the parameter ${\\alpha}_{\\pi\\pi}$ defining the tree level $\\pi - \\pi$ scattering amplitude and on an additional low energy constant. The latter is shown to be related by an exact sum-rule to the $e^+ e^-$ data. The parameter ${\\alpha}_{\\pi\\pi}$ is related to the quark mass ratio $r = m_s /{\\hat m}$ via the expansion of pseudoscalar meson masses. The "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ph/9402318","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/hep-ph/9402318/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}