Nonlocal condensates and QCD sum rules for the pion wave function
Mikhailov S. V., Radyushkin A. V.
The QCD sum rules for the moments of the pion wave function <p„ (x) are extremely sensitive to the coordinate dependence of "nonlocal condensates": ( q(0)q(z))=M(z 2), {ξ{0)γμ q(z)), etc. Modified sum rules are derived. An explicit expression φπ(χ)~ (8/тг) fnyfic( 1 — χ) is found for distributions M(z 2) having the width dictated by the standard value (Я 2 — 0.4 GeV2) of the ratio Я 2 = (qD2q).(qq).
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![](/ps/1413/article_21499_800_head.png "The QCD sum rules for the moments of the pion wave function <i><p„ (x) </i>are extremely sensitive to the coordinate dependence of "nonlocal condensates": <i>( q(0)q(z))=M(z </i><sup>2</sup>), <i>{ξ{0)γ<sub>μ</sub> q(z)), </i>etc. Modified sum rules are derived. An explicit expression <i>φ<sub>π</sub>(χ)~ </i>(8/тг) <i>f<sub>n</sub>yfic( </i>1 — <i>χ) </i>is found for distributions <i>M(z <sup>2</sup>) </i>having the width dictated by the standard value (Я <sup>2</sup> — 0.4 GeV<sup>2</sup>) of the ratio Я <sup>2 </sup><i>= (qD<sup>2</sup>q).(qq).</i>")