Hadron radii and the origin of chiral singularities

Hadron radii are discussed with particular emphasis on chiral singularities m(PS)(-1) and log mps; those result from the photon coupling to the (PS PS) continuum and are, therefore, most visible in isovector electromagnetic radii. It is shown that OZI rule violation leads to m(K)(-1) and log m(K)- terms in the isoscalar radii as well. The gamma pi pi pi vertex function is free of chiral singularities and so are all quark core contributions. The Delta(1232) contribution is particularly important for the subleading log m (pi-) terms, where a delicate cancellation occurs with pion loop contributi ons of the same order.