1993
DOI: 10.1103/physrevlett.71.484
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Direct instantons in QCD nucleon sum rules

Abstract: We study the role of direct (i.e. small-scale) instantons in QCD correlation functions for the nucleon. They generate sizeable, nonperturbative corrections to the conventional operator product expansion, which improve the quality of both QCD nucleon sum rules and cure the long-standing stability problem, in particular, of the chirally odd sum-rule.12.38. Lg, 14.20.Dh Typeset using REVT E X 1 QCD sum rules, introduced by Shifman, Vainshtein and Zakharov (SVZ) [1], provide a systematic, nonperturbative framew… Show more

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Cited by 51 publications
(76 citation statements)
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References 26 publications
(45 reference statements)
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“…Indications supporting this expectation have been found in an analogous study of the nucleon correlation functions [19]. The applicabilty of the sum rule at small Q 2 would then be mainly limited by the unphysical singularity in the perturbative contribution (13). [6].…”
mentioning
confidence: 55%
See 1 more Smart Citation
“…Indications supporting this expectation have been found in an analogous study of the nucleon correlation functions [19]. The applicabilty of the sum rule at small Q 2 would then be mainly limited by the unphysical singularity in the perturbative contribution (13). [6].…”
mentioning
confidence: 55%
“…In order to allow for a direct comparison with the instanton analysis of the two-point correlator [5], which takes K = 0.7 GeV, we fix K at the lower limit of the phenomenologically acceptable range, K = 1.0 GeV. The effective mass m * , finally, is determined as in [5,13] from the self-consistency relation [8] for the quark condensate, qq = −2n/m * (ρ).…”
mentioning
confidence: 99%
“…In contrast to previously studied IOPE sum rules for quark-based correlators [14,15], those for the scalar glueball are the first where (i) the instanton contributions do not enter via topological quark zero-modes and (ii) the sum rules reach a satisfactory (though not excellent) level of consistency even without any perturbative and soft contributions, i.e., with the instanton terms alone. The latter result explains why the instanton liquid model yields scalar glueball properties similar to those obtained above [10], and can be traced to both the exceptional strength and the particular shape (mainly the curvature) of the instanton contributions.…”
Section: Discussionmentioning
confidence: 82%
“…[9]). Analogous contributions were found to be important in several nucleon [14] and pion [15] To leading order in the semiclassical approximation, the instanton contribution to Eq.…”
Section: Iope and Sum Rulesmentioning
confidence: 99%
“…Further, in the chiral-even sum rule the single pole term corresponding to transition between proton and the excited states dominated over the double pole term. We would also like to point out that inclusion of instanton contributions improves the chiral-even mass sum rule [31]. In the light of our observations above regarding the relation of our sum rules to the mass sum rules it suggests that such instanton contributions can also be significant in our sum rule Eq.…”
Section: Discussionmentioning
confidence: 88%