paper

QCD-Based Interpretation of the Lepton Spectrum in Inclusive Decays

arXiv:hep-ph/9311325 · doi:10.1103/PhysRevD.49.3392

Abstract

We present a QCD-based approach to the endpoint region of the lepton spectrum in decays. We introduce a genuinely nonperturbative form factor, the shape function, which describes the fall-off of the spectrum close to the endpoint. The moments of this function are related to forward scattering matrix elements of local, higher-dimension operators. We find that nonperturbative effects are dominant over a finite region in the lepton energy spectrum, the width of which is related to the kinetic energy of the -quark inside the meson. Applications of our method to the extraction of fundamental standard model parameters, among them , are discussed in detail.

17 pages LaTeX, 3 post- script figures available upon request, CERN-TH.7087/93

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