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Fragmentation Functions for Lepton Pairs

Eric Braaten·Jungil Lee
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Abstract

We calculate the fragmentation function for a light quark to decay into a lepton pair to leading order in the QCD coupling constant. In the formal definition of the fragmentation function, a QED phase must be included in the eikonal factor to guarantee QED gauge invariance. We find that the longitudinal polarization fraction is a decreasing function of the factorization scale, in accord with the intuitive expectation that the virtual photon should behave more and more like a real photon as the transverse momomentum of the fragmenting quark increases.

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Eric Braaten, Jungil Lee. 2001-02-17. Fragmentation Functions for Lepton Pairs. https://doi.org/10.1103/physrevd.65.034005

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