Abstract

We discuss the continuation of asymptotically free quark model predictions for e +e − → hadrons in the complex q 2 plane from spacelike to near timelike regions. At currently available energies we find we must compute gluon corrections to both the real and imaginary parts of the hadronic vacuum polarization tensor. Using quark masses defined by the position of the pole in the quark propagator we find good fits to the smeared data for a variety of models. However, use of an “off pole” definition of quark masses leads to a breakdown of the perturbation expansion even in regions far away from the real axis. Fits to the data outside these regions give highly correlated results dependent on the value of the strong coupling constant and the masses of the heavy quarks or leptons present. For a choice of the strong coupling constant consistent with observed scale violations in electroproduction, we find the data favors five quark flavors with a fifth quark of “mass” 2.3 GeV and a heavy lepton of mass ⋍ 2 GeV.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call