Dresden 2000 – scientific programme
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T: Teilchenphysik
T 401: QCD 4
T 401.9: Talk
Tuesday, March 21, 2000, 18:30–18:45, H\,01
Instantons and higher–twist contributions to the nucleon structure function x F3(x,Q2) — •G. Aronica, B. Dressler, K. Goeke, Nam–Young Lee, and C. Weiss — Institut f. Theoretische Physik II, Ruhr–Universität Bochum
For the nucleon’s weak current structure function, xF3(x,Q2), new precise data are now available from the CCFR neutrino scattering experiment. An interesting theoretical problem is the magnitude of a possible twist–4 contribution in the Q2–dependence of this structure function, which in QCD is caused by nonperturbative correlations of the quark and gluon fields in the nucleon. We compute the relevant twist–4 nucleon matrix elements (both flavor–singlet and nonsinglet) within the instanton–based picture of the QCD vacuum [1]. We compare our results with the phenomenological twist–4 contributions extracted from QCD fits to the data [2].
[1] J.Balla, M.V. Polyakov, and C. Weiss, Nucl. Phys. B 510, 327 (1997)
[2] S.I. Alekhin and A.L. Kataev, Phys. Lett. B 452, 402 (1999)