Recent developments in the constituent quark model including quark-antiquark pairs

Abstract

We present the formalism for a new generation of unquenched quark models for baryons in which the effects of quark-antiquark pairs (u anti-u, d anti-d and s anti-s) are taken into account in an explicit form via a microscopic, QCD-inspired, quark-antiquark creation mechaniscm. The present approach is an extension of the flux-tube breaking model of Geiger and Isgur in which now the contributions of quark-antiquark pairs an be studied for any initial baryon and for any flavor of the q anti-q pair. It is shown that the inclusion of q anti-q paris leads to a large contribution of orbital angular momentum to the proton spin.

Comments: 5 pages, 4 figures, 2 tables, NSTAR2007, Proceedings of the 11th Workshop on the Physics of Excited Nucleons, Springer, 2008