Unexpected features of e+e- → p(p)over-bar and e+e- → Λ(Λ)over-bar cross-sections near threshold

Unexpected features of the BaBar data on e(+)e(-) -> B (B) over bar cross-sections (B stands for baryon) are discussed. These data have been collected, with unprecedented accuracy, by means of the initial-state radiation technique, which is particularly suitable in giving good acceptance and energy resolution at threshold. A striking feature observed in the BaBar data is the non-vanishing cross-section at threshold for all these processes. This is the expectation due to the Coulomb enhancement factor acting on a charged fermion pair. In the case of e(+)e(-) -> p (p) over bar it is found that Coulomb final-state interactions largely dominate the cross-section and the form factor is vertical bar G(p)(4M(p)(2))vertical bar similar to 1, which could be a general feature for baryons. In the case of neutral baryons an interpretation of the non-vanishing cross-section at threshold is suggested, based on quark electromagnetic interaction and taking into account the asymmetry between attractive and repulsive Coulomb factors. Besides strange baryon cross-sections are compared to U-spin invariance predictions.