PI-NN AND PSEUDOSCALAR FORM-FACTORS FROM LATTICE QCD

The NN form factor gNN(q2) is obtained from a quenched lattice QCD calculation of the pseudoscalar form factor gP(q2) of the proton with pion pole dominance. We find that gNN(q2) is well fitted with a monopole form which agrees with the Goldberger-Treiman relation. The monopole mass is determined to be 0.75 0.14 GeV, which shows that gNN(q2) is rather soft. The extrapolated N coupling constant gNN=12.7 2.4 is quite consistent with the phenomenological values. We also compare gNN(q2) with the axial form factor gA(q2) to check pion dominance in the induced pseudoscalar form factor hA(q2) vis-à-vis the chiral Ward identity. © 1995 The American Physical Society.