OMEGA-NN VERTEX FUNCTION AND THE GAMMA-PI-PI-PI ANOMALY

We show that the empirical omega NN form factor (cut-off 1400-1500 MeV ) can be understood as arising from a combination of a quark model for m factor (typical cutoff 700-800 MeV) and an anomalous form factor sim ilar to q(2) arising from the 3 pi-intermediate state. The anomaly con tributes to the Dirac form factor F-1(q(2)) with F-1(0) = 0, -d/dq(2)F (1)(q(2))\(q2=0) > 0 (and sizable), and to the Pauli form factor F-2(q (2)) with F-2(0) not equal 0. The resulting tensor coupling F-2(0) is sensitive to the cut-off of the pion momenta in the two-loop integrals and turns out to be small for values around 1 GeV. The quark model om ega NN tensor coupling F-2(0) vanishes for point-like quarks. The anom aly, however, contributes a non-vanishing tensor coupling which can be seen to effectively enhance the vector coupling in NN models which do not include a tensor coupling.