Transverse parton momenta in single inclusive hadron production in e+e− annihilation processes

M Boglione,J.O Gonzalez-Hernandez,R Taghavi

doi:10.1016/j.physletb.2017.06.034

Abstract

We study the transverse momentum distributions of single inclusive hadron production in e+e− annihilation processes. Although the only available experimental data are scarce and quite old, we find that the fundamental features of transverse momentum dependent (TMD) evolution, historically addressed in Drell–Yan processes and, more recently, in Semi-inclusive deep inelastic scattering processes, are visible in e+e− annihilations as well. Interesting effects related to its non-perturbative regime can be observed.We test two different parameterizations for the p⊥ dependence of the cross section: the usual Gaussian distribution and a power-law model. We find the latter to be more appropriate in describing this particular set of experimental data, over a relatively large range of p⊥ values. We use this model to map some of the features of the data within the framework of TMD evolution, and discuss the caveats of this and other possible interpretations, related to the one-dimensional nature of the available experimental data.

Highlights

The only available experimental data are scarce and quite old, we find that the fundamental features of transverse momentum dependent (TMD) evolution, historically addressed in Drell–Yan processes and, more recently, in Semi-inclusive deep inelastic scattering processes, are visible in e+e− annihilations as well
Transverse momentum dependent distribution and fragmentation functions (TMDs) are fundamental tools to understand the structure of nucleons in terms of their elementary constituents, quarks and gluons
Unpolarized and polarized TMD distribution functions have extensively been studied in Drell–Yan processes and semi-inclusive deep inelastic scattering (SIDIS) in the past; new-generation, dedicated experiments are currently running or are being planned

Summary

Introduction

Transverse momentum dependent distribution and fragmentation functions (TMDs) are fundamental tools to understand the structure of nucleons in terms of their elementary constituents, quarks and gluons. Together with TASSO data, we consider the analogous MARKII Collaboration measurements [13], collected at the SLAC storage ring PEP, at a fixed c.m. energy of 29 GeV, and PLUTO data on the average transverse momentum square [14], collected at PETRA (DESY) Crucial to all these data is the correct determination of the jet axis, to which the p⊥ distributions are most sensitive, beside proper treatment of geometric acceptance effects, trigger bias, kinematics cuts and radiative corrections. Lower panel: center of mass energies corresponding to PLUTO measurements of p2⊥

14 GeV 22 GeV 35 GeV 44 GeV

Formalism

Data fitting and results

Final remarks