Document Type

Article

Publication Date

2025

DOI

10.1103/PhysRevD.111.056001

Publication Title

Physical Review D

Volume

111

Issue

5

Pages

056001 (1-29)

Abstract

Important aspects of quantum chromodynamics (QCD) factorization theorems are the properties of the objects involved that can be identified as universal. One example is that the definitions of parton densitiesand fragmentation functions for different types of hadrons differ only in the identity of the nonperturbative states that form the matrix elements, but are otherwise the same. This leads to independence of perturbativecalculations on nonperturbative details of external states. It also lends support to interpretations ofcorrelation functions as encapsulations of intrinsic nonperturbative properties. These characteristics have usually been presumed to still hold true in fragmentation functions even when the observed nonperturbative state is a small-mass cluster of nhadrons rather than simply a single isolated hadron. However, themultidifferential aspect of cross sections that rely on these latter types of fragmentation functionscomplicates the treatment of kinematical approximations in factorization derivations. That has led to recent claims that the operator definitions for fragmentation functions need to be modified from the single hadron case with nonuniversal prefactors. With such concerns as our motivation, we retrace the steps for factorizing the unpolarized semi-inclusive e⁺e⁻ annihilation cross section and confirm that they do applywithout modification to the case of a small-mass multihadron observed in the final state. In particular, we verify that the standard operator definition from single hadron fragmentation, with its usual prefactor, remains equally valid for the small-mass n-hadron case with the same hard parts and evolution kernels, whereas the more recently proposed definitions with nonuniversal prefactors do not. Our results reaffirm the reliability of most past phenomenological applications of dihadron fragmentation functions.

Rights

© 2025 The Authors.

Published under the terms of the Creative Commons Attribution 4.0 International License. Further distribution of this work must maintain attribution to the authors and the published article's title, journal citation, and DOI. Funded by SCOAP³.

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Original Publication Citation

Rogers, T. C., Radici, M., Courtoy, A., & Rainaldi, T. (2025). QCD factorization with multihadron fragmentation functions. Physical Review D, 111(5), 1-29, Article 056001. https://doi.org/10.1103/PhysRevD.111.056001

ORCID

0000-0002-0762-0275 (Rogers), 0000-0002-8342-6765 (Rainaldi)

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