Eur. Phys. J. C 29, 71-78 (2003)
DOI: 10.1140/epjc/s2003-01218

On the instanton-induced portion of the nucleon strangeness II: the MIT model beyond the linearized approximation

D. Klabucar¹, K. Kumericki¹, D. Mekterovic² and B. Podobnik<sup>1

1</sup>  Department of Physics, Faculty of Science, University of Zagreb, Bijenicka c. 32, 10000 Zagreb, Croatia
²  Rudjer Boskovic Institute, P.O. Box 180, 10002 Zagreb, Croatia

klabucar@phy.hr
kkumer@phy.hr
dmekter@rudjer.irb.hr
bp@phy.hr

(Received: 7 February 2003 / Revised version: 1 April 2003 / Published online: 23 May 2003 )

Abstract
If instantons are introduced into the MIT bag model in such a way that the bag radii are allowed to vary, the MIT bag interior can accommodate an instanton density which is by an order of magnitude larger than in the case when the radii are fixed (although it is still significantly smaller than in the non-perturbative QCD vacuum). The instanton contribution to the baryon mass shifts is also correspondingly larger. The instanton-induced part of the scalar strangeness of the nucleon MIT bag is an order of magnitude larger than found previously, within the linearized approximation. The decrease of the model radii (which is associated with the increase of the instanton density) is very favorable from the standpoint of nuclear physics.

© Società Italiana di Fisica, Springer-Verlag 2003