  Exclusive baryon pair production through the radiative return is a unique
tool to determine the electric and the magnetic form factors in the timelike
region over a wide range of energies. The decay of lambda-baryons into p + pi-
can be used to measure their spin and to analyze spin-spin correlations in the
antilambda-lambda system. We evaluate the spin dependent hadronic tensor, which
describes this reaction, calculate the corresponding cross section for e+e- ->
antilambda lambda and e+e- -> antilambda lambda gamma with subsequent decays of
lambda and antilambda and present a compact formula for the correlated
distribution. We demonstrate that the relative phase between the electric and
the magnetic form factor can be determined in this analysis by considering
single spin asymmetries and correlated decay distributions. The reaction is
implemented in the event generator PHOKHARA. It is demonstrated that the
relative phase can be measured with the event sample presently accumulated at
B-factories.
