Dresden 2000 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HK: Physik der Hadronen und Kerne
HK 14: Postersitzung / Theorie
HK 14.20: Poster
Donnerstag, 23. März 2000, 10:15–12:45, B 113
Power corrections and intrinsic charm contribution to g1 (x, Q2 ) from instantons — •Nam–Young Lee1, K. Goeke1, M.V. Polyakov1,2, and C. Weiss1 — 1Institut f. Theoretische Physik II, Ruhr–Universität Bochum — 2Petersburg Nuclear Physics Institute, Russia
In QCD, power (1/Q2–) corrections to the first moment of the polarized structure function g1 (x, Q2) are governed by nucleon matrix elements of operators of twist 3 and 4, which measure the non-perturbative correlations of the quark and gluon fields in the nucleon. We compute these matrix elements (both isovector and isosinglet) in the instanton–based description of the QCD vacuum [1]. We use the results to estimate the corrections to the Q2–dependence of the first moments of g1p and g1n (Bjorken and Ellis–Jaffe sum rules) in the non-perturbative region. The flavor–singlet twist–4 matrix element, fS(2), also determines the so-called intrinsic charm contribution (of order 1/mc2) to the nucleon spin [2]. With the instanton vacuum result for fS(2) we obtain a very small value of this contribution, of the order of 10−4.
[1] J.Balla, M.V. Polyakov, and C. Weiss, Nucl. Phys. B 510, 327 (1997)
[2] M.V. Polyakov, A. Schäfer, and O.V. Teryaev, Phys. Rev. D60 (1999) 051502.