Status of R value measurement at BESIII

The dominant systematic error of R value measurement comes from the hadronic generator simulations. This paper reviews the present status of R value measurement from 2.232 to 3.671 GeV at 14 energy points, especially describes the calculations of initial state radiative correction and the issue of the parameter tuning for the Lund area law generator LUARLW.

OFF-SHELL Z0 PAIR PRODUCTION IN e+e− ANNIHILATION

A study of the standard model reaction [Formula: see text] including the effects of the finite Z0 width and initial state radiative corrections is presented. All angular phase space integrations are performed analytically. The remaining invariant masses are integrated numerically. Semianalytical and numerical results in the energy range [Formula: see text] to 1 TeV are reported. The generalization of the analytical method to include photon exchange and also models with more neutral gauge bosons is outlined.