Unexpected features of e+e-->ppbar and e+e-->lambda-lambdabar cross sections near threshold

Understand

Unexpected features of the BaBar data on e+e- in baryon-antibaryon cross sections 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.