Perturbative QCD Fragmentation Functions as a Model for Heavy-Quark Fragmentation

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The perturbative QCD fragmentation functions for a heavy quark to fragment into heavy-light mesons are studied in the heavy-quark limit. The fragmentation functions for S-wave pseudoscalar and vector mesons are calculated to next-to-leading order in the heavy-quark mass expansion using the methods of heavy-quark effective theory. The results agree with the mb→ ∞ limit of the perturbative QCD fragmentation functions for b into Bc and Bc*. We discuss the application of the perturbative QCD fragmentation functions as a model for the fragmentation of heavy quarks into heavy-light mesons. Using this model, we predict the fraction Pᵥ of heavy-light mesons that are produced in the vector meson state as functions of the longitudinal momentum fraction z and the transverse momentum relative to the jet axis. The fraction Pᵥ is predicted to vary from about 1/2 at small z to almost 3/4 near z=1.