In e+e- annihilation, are the jets that are produced quarks and gluons, or hadrons? What is the basic idea behind a QCD calculation for such a process? For example, do I take the two initial states to be e+e-, and the two final states to be q+q- (quark and antiquark), but also add the possibility of emission of low-energy gluons and quarks (in much the same way one treats infrared divergences of soft photons in QED)? Also, if the particles in jets are hadrons and not a stream of quarks and gluons, how does one represent them in QCD calculations? I'm only aware of representing hadrons in the context of effective field theories below the QCD scale .2 GeV, but these experiments are at much higher energies. Also, what about cross-section for e+e- to go into a lepton+antilepton- pair rather than a quark+antiquark- pair? Does this become negligible at these energies?