Abstract
This study is part of a project to investigate the transverse momentum dependence in parton dis- tribution and fragmentation functions, analyzing (semi-)inclusive high-energy processes within a proper QCD framework. We calculate the transverse-momentum-dependent (TMD) multiplicities for e + e − annihilation into two hadrons (considering different combinations of pions and kaons) aiming to investigate the impact of in- trinsic and radiative partonic transverse momentum and their mixing with flavor. Different descriptions of the non-perturbative evolution kernel (see, e.g., Refs. (1-5)) are available on the market and there are 200 sets of flavor configurations for the unpolarized TMD fragmentation functions (FFs) resulting from a Monte Carlo fit of Semi-Inclusive Deep-Inelastic Scattering (SIDIS) data at Hermes (see Ref. (6)). We build our predictions of e + e − multiplicities relying on this rich phenomenology. The comparison of these calculations with future experimental data (from Belle and BaBar collaborations) will shed light on non-perturbative aspects of hadron structure, opening important insights into the physics of spin, flavor and momentum structure of hadrons.
Highlights
The QCD description of electron-positron annihilation into hadrons with observed transverse momenta in the final states requires the usage of TMD fragmentation functions (FFs)
In this work we present predictions for transverse momentum dependence in pion and kaon multiplicities related to electron-positron annihilation into two hadrons
Choosing the QCD evolution framework in Ref. [9] dressed with a model for low partonic transverse momenta inspired to Refs. [1, 2, 6], we found evidence of a good sensitivity of the predictions to the non-perturbative parameters involved in the calculations
Summary
We calculate multiplicities for annihilation into two hadrons, focusing on the input brought by nonperturbative QCD. The contribution coming from gluons radiated with low transverse momentum by the fragmenting quark must be phenomenologically parametrized and different choices drive to different shapes in the multiplicity. The second source of non-perturbative information that we take into account is the flavor structure of TMD FFs. Previous analyses [6,7,8]) revealed that the the TMD part of FFs depends on the quark flavor, confirming the physically intuitive picture of quarks fragmenting into different hadrons with different probability amplitudes. We investigate to which extent the annihilation rate is modified according to different flavor configurations for the intrinsic transverse momentum of quarks
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