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Virtual photon fragmentation functions

Jianwei Qiu·Xiaofei Zhang
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Abstract

We introduce operator definitions for virtual photon fragmentation functions, which are needed for reliable calculations of Drell-Yan transverse momentum ($Q_T$) distributions when $Q_T$ is much larger than the invariant mass $Q$. We derive the evolution equations for these fragmentation functions. We calculate the leading order evolution kernels for partons to fragment into a unpolarized as well as a polarized virtual photon. We find that fragmentation functions to a longitudinally polarized virtual photon are most important at small $z$, and the fragmentation functions to a transversely polarized virtual photon dominate the large $z$ region. We discuss the implications of this finding to the J/$ψ$ mesons' polarization at large transverse momentum.

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Jianwei Qiu, Xiaofei Zhang. 2001-02-11. Virtual photon fragmentation functions. https://doi.org/10.1103/physrevd.64.074007

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