https://doi.org/10.1140/epjc/s10052-020-08821-y
Regular Article – Theoretical Physics
Universality-breaking effects in 
hadronic production processes
1
Dipartimento di Fisica Teorica, Università di Torino, Via P. Giuria 1, 10125, Turin, Italy
2
INFN, Sezione di Torino, Via P. Giuria 1, 10125, Turin, Italy
Received:
31
October
2020
Accepted:
28
December
2020
Published online:
30
January
2021
Recent BELLE measurements provide the cross section for single hadron production in annihilations, differential in thrust and in the hadron transverse momentum with respect to the thrust axis. Universality breaking effects due to process-dependent soft factors make it very difficult to relate this cross sections to those corresponding to hadron-pair production in annihilations, where transverse momentum dependent (TMD) factorization can be applied. The correspondence between these two cross sections is examined in the framework of the Collins-Soper-Sterman factorization, in the collinear as well as in the TMD approach. We propose a scheme that allows to relate the TMD parton densities defined in 1-hadron and in 2-hadron processes, neatly separating, within the soft and collinear parts, the non-perturbative terms from the contributions that can be calculated perturbatively. The regularization of rapidity divergences introduces cut-offs, the arbitrariness of which will be properly reabsorbed by means of a mechanism closely reminiscent of a gauge transformation. In this way, we restore the possibility to perform global phenomenological studies of TMD physics, simultaneously analyzing data belonging to different hadron classes.
© The Author(s) 2021
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