We present preliminary results of an exploratory lattice study of the vector
form factor f1(q2=0) relevant for the semileptonic hyperon decay
Σ−−−>nlν. This study is based on the same method used for the
extraction of f+(0) for the decay K0−−>π−lν. The main purpose
of this study is to test the method for hyperon form factors in order to
estimate the precision that can be reached and the importance of SU(3)-breaking
effects.Comment: 3 pages, 5 figures, talk presented at Lattice2004(weak), Fermilab,
Batavia, Illinois, 21-26 June 200