TY - JOUR

T1 - Use and misuse of QCD sum rules, factorization and related topics

AU - Novikov, V. A.

AU - Shifman, M. A.

AU - Vainshtein, A. I.

AU - Voloshin, M. B.

AU - Zakharov, V. I.

PY - 1984/5/21

Y1 - 1984/5/21

N2 - 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.

AB - 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.

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U2 - 10.1016/0550-3213(84)90006-3

DO - 10.1016/0550-3213(84)90006-3

M3 - Article

AN - SCOPUS:0002741975

VL - 237

SP - 525

EP - 552

JO - Nuclear Physics B

JF - Nuclear Physics B

SN - 0550-3213

IS - 3

ER -