A Dynamical Eta'-Mass from an Infrared Enhanced Gluon Exchange
The pseudo-scalar flavor-singlet meson mixes with two gluons. A dimensional argument by Kogut and Susskind shows that this can screen the Goldstone pole of the chiral limit in this channel, if the gluon correlations are infrared enhanced. Using a gluon propagator as singular as sigma/k^4 for k^2 -> 0 we relate the screening mass to the string tension sigma. In the Witten-Veneziano action to describe the eta-eta' mixing this relation yields masses of about 810MeV for the eta', 430MeV for the eta and a mixing angle of about -30deg from the phenomenological value for sigma of approx. 0.18GeV^2. The very weak temperature dependence of the string tension should make this mechanism experimentally distinguishable from exponentially temperature dependent instanton model predictions.