Use and misuse of QCD sum rules, factorization and related topics

V. A. Novikov, M. A. Shifman, A. I. Vainshtein, M. B. Voloshin, V. I. Zakharov

Research output: Contribution to journalArticlepeer-review

255 Scopus citations

Abstract

The purpose of this paper is twofold. First, we are prompted by some recent publications to reply to the criticism of the QCD sum-rules approach contained therein. Hopefully, some of the discussion is of wider interest. In particular, we point out that the multi-gluon operators unlike the multi-quark ones, relevant to the sum rules, do not factorize at large Nc. This implies that the masterfield, even if it is found, will be of no immediate help in evaluating the quarkonium spectrum. Second, we derive new sum rules for light quarks which are sensitive to the mean intensity of the gluon field in the vacuum (the so-called gluon condensate, or 〈vac|G2|vac〉). New sum rules confirm the standard value of 〈vac|G2|vac〉. Some casual remarks on the π0 transitions into two virtual photons, π0 → γ*γ*, are also presented. Finally, we enumerate (in sect. 7) basic points of the sum-rule approach and discuss, im brief, the unsolved problems.

Original languageEnglish (US)
Pages (from-to)525-552
Number of pages28
JournalNuclear Physics, Section B
Volume237
Issue number3
DOIs
StatePublished - May 21 1984

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