### Abstract

Current all-orders proofs of factorization of hard processes are made by extracting the leading power behavior of Feynman graphs, i.e., by extracting asymptotics strictly order-by-order in perturbation theory. The resulting parton densities and fragmentation functions include nonperturbative effects. I show how there are missing elements in the proofs; these are related to and exemplified by string and cluster models of hadronization. The proofs rely on large rapidity differences between different parts of graphs for the process; but in reality large rapidity gaps are filled in.

Original language | English (US) |
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Journal | Proceedings of Science |

Volume | Part F128562 |

State | Published - Jan 1 2016 |

Event | 2016 QCD Evolution Workshop, QCDEV 2016 - Amsterdam, Netherlands Duration: May 30 2016 → Jun 3 2016 |

### All Science Journal Classification (ASJC) codes

- General

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## Cite this

Collins, J. (2016). Do fragmentation functions in factorization theorems correctly treat non-perturbative effects?

*Proceedings of Science*,*Part F128562*.