Gluonic effects in eta'-nucleon interactions

Abstract

We review the theory and phenomenology of the axial U(1) problem with emphasis on the role of gluonic degrees of freedom in the low-energy pp -> pp eta and pp -> pp eta' reactions.

13 pages, 2 figures, invited lecture at the Symposium on Threshold Meson Production in pp and pd interactions, June 2001, Cracow, Poland