Aspects of anomalous glue
  Non-perturbative glue associated with gluon topology plays a vital role in determining the mass of the etaprime meson. We give an introduction to axial U(1) physics and explain how this non-perturbative glue also contributes to etaprime interactions with other hadrons. We concentrate on resonant etaprime pi production in partial waves with exotic quantum numbers not compatible with a quark-antiquark state and on the etaprime in nuclear media where there are new results from the COMPASS and CBELSA/TAPS experiments respectively. 
Steven D. Bass
hep-ph