Transverse Momentum Dependent Fragmentation Functions from recent BELLE data

TL;DR

This paper introduces a new formalism for analyzing transverse momentum dependent fragmentation functions in electron-positron annihilation data, applying it to recent BELLE measurements and exploring the non-perturbative modeling of these functions.

Contribution

It develops a novel factorization scheme for single hadron production cross sections and assesses the experimental constraints on the non-perturbative TMD fragmentation functions.

Findings

Next-to-leading order calculation of the perturbative part.

Evaluation of different models for non-perturbative TMD fragmentation functions.

Data constrains the shape of the non-perturbative functions in certain kinematic regions.

Abstract

A new formalism for the factorization of the cross section for single hadron production in $e^+e^-$ annihilations, differential in $z_h$, $P_T$ and thrust, is applied to the phenomenological analysis of data recently measured by the BELLE Collaboration. Within this scheme the $e^+e^- \to hX$ cross section can be recast in the convolution of a perturbatively calculable coefficient and a universal transverse momentum dependent fragmentation function. While performing a next-to-leading order calculation of the perturbative part of the process to next-to-leading logarithmic accuracy, we examine and thoroughly discuss the suitability of a number of possible ansatz to model the non-perturbative part of this universal transverse momentum dependent fragmentation function, showing the extent to which present experimental data can actually constrain its shape and functional form in terms of $z_h$, $P_T$ and thrust.