Electromagnetic |GE/GM| ratios of hyperons at large timelike q²

In recent years, it has become possible to measure not only the magnitude of the electric (GE) and magnetic (GM) form factors of spin 12 baryons, but also to measure the relative phases of those quantities in the timelike kinematic region. Aiming to interpret present |GE/GM| data on hyperons of the baryon octet, as well as to predict future data, we present model calculations of that ratio for large invariant 4-momentum square q² in the timelike region (q²>0). Without any further parameter fitting, we extend to the timelike region a covariant quark model previously developed to describe the kinematic spacelike region (q² 0) of the baryon octet form factors. The model takes into account both the effects of valence quarks and the excitations of the meson cloud which dresses the baryons. We report here that our results are in good agreement with very recent data from BESIII, within the uncertainty limits of our model. We also make new predictions which may be tested in the near future, when the range of the present measurements is expanded to the 20--50 GeV² region.