Form factor of the process γ^*γ^* -->π^o for small Virtuality of One of the Photons and QCD Sum Rules

1995/07/28 by Anatoly Radyushkin, A. V. Radyushkin, Radyushkin, A. V. +3
Mathematics · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #advanced mathematical theories #hep-ph

paper · pdf · doi:10.48550/arxiv.hep-ph/9507447

6 pages, uses epsf.sty, 1 eps figure

openalex publication_date 1995/07/28 · arxiv created 1995/07/29 · arxiv updated 2009/11/30 · openalex created_date 2024/04/11 · openalex updated_date 2026/07/28

Abstract

We extend the QCD sum rule analysis of the γ^*γ^* -->π^o form factor into the region where one of the photons has small virtuality: q² << Q² > 1 GeV². In this kinematics, one should perform an additional factorization of short- and long-distance contributions. The extra long-distance sensitivity of the three-point amplitude is described by two-point correlators (bilocals), and the low-momentum dependence of the correlators involving composite operators of two lowest twists is extracted from auxiliary QCD sum rules. Our estimates for the form factor at q²=0, Q² > 1 1 GeV² are in good agreement with existing experimental data.

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