Nucleon strangeness and unitarity

The strange-quark vector current form factors of the nucleon are analyzed within the framework of dispersion relations. Particular attention is paid to contributions made by K bar K intermediate states to the form factor spectral functions. It is shown that, when the K bar K→N bar N amplitude is evaluated in the Born approximation, the K bar K contributions are identical to those arising from a one-loop calculation and entail a serious violation of unitarity. The mean square strangeness radius and magnetic moment are evaluated by imposing unitarity bounds on the kaon-nucleon partial wave amplitudes. The impact of including the kaon close-quote s strangeness vector current form factor in the dispersion integrals is also evaluated. copyright 1997 The American Physical Society