Semiexclusive production in electron-positron annihilation.

We present a thorough analysis of the direct semiexclusive production in quantum chromodynamics (QCD) of single, highly isolated mesons from electron-positron or two-photon initial states. Corrections of higher order and of subleading twist are considered, and potential divergences in the naive calculation are contained. Monte Carlo methods are used to relate the QCD calculations to experimentally measurable quantities. We nd that the study of semiexclusive production is the most sensitive experimental probe of the structure of mesons in the valence (q q) state at energies s > 10 GeV. Submitted to Physical Review D ? Work supported by Department of Energy contract DE{AC03{76SF00515.