CHIRAL CORRECTIONS TO HYPERON VECTOR FORM-FACTORS

We show that the leading chiral corrections to the DELTAS = 1 f1 vector form factors of hyperons are O(m(s)) and O(m(s) 3/2), and are expected to be approximately 20-30 % by dimensional analysis. This is consistent with the Ademollo-Gatto theorem. We compute the O(m(s)) corrections and a subset of the O(m(s)3/2) corrections using an effective Lagrangian in which the baryons are treated as heavy particles. All of these corrections are surprisingly small, approximately 5%; combining them, we obtain approximately 5-10 % corrections. The pattern of corrections is very different from that predicted by quark models.