{"paper":{"title":"The $\\gamma^* \\gamma^*\\to\\eta_c$ transition form factor","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"Dmitri Melikhov, Wolfgang Lucha","submitted_at":"2012-05-21T13:02:55Z","abstract_excerpt":"We study the $\\gamma^* \\gamma^*\\to\\eta_c$ transition form factor, $F_{\\eta_c\\gamma\\gamma}(Q_1^2,Q_2^2),$ with the local-duality (LD) version of QCD sum rules. We analyse the extraction of this quantity from two different correlators, $<PVV>$ and $<AVV>,$ with $P,$ $A,$ and $V$ being the pseudoscalar, axial-vector, and vector currents, respectively. The QCD factorization theorem for $F_{\\eta_c\\gamma\\gamma}(Q_1^2,Q_2^2)$ allows us to fix the effective continuum thresholds for the $<PVV>$ and $<AVV>$ correlators at large values of $Q^2=Q_2^2$ and some fixed value of $\\beta\\equiv Q_1^2/Q_2^2$. We "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1205.4587","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":""},"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"}