Pion distribution amplitude and form-factors: Improved Gaussian model of QCD vacuum
Abstract
We describe the present status of the pion distribution amplitude (DA) as it originated from several sources: (i) a nonperturbative approach, based on QCD sum rules with nonlocal condensates, (ii) an O(αs) QCD analysis of the CLEO data on Fγγ*π(Q2) with asymptotic and renormalon models for higher twists, and (iii) recent high-precision lattice QCD calculations of the second moment of the pion DA. Then we show the comparison of the results for the pion electromagnetic form factor, obtained in analytic perturbation theory, with JLab data on Fπ(Q2). After that we introduce the improved model for nonlocal condensates in QCD and show its consequences for the pion DA and γγ*π transition form factor. In order to facilitate possible applications of BMS and improved ``bunches'' we suggest approximate analytic descriptions of their boundaries.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.