Determination of contributions from residual light charged hadrons to inclusive charged hadrons from $e^+e^-$ annihilation data

TL;DR

This study extracts the small but significant residual contributions of light charged hadrons to inclusive charged hadron fragmentation functions at NLO and NNLO, improving the accuracy and reliability of QCD fits in electron-positron annihilation data.

Contribution

It introduces the first NNLO analysis of residual light charged hadron FFs, enhancing understanding of their impact on inclusive hadron production in QCD.

Findings

Residual contributions significantly affect inclusive charged hadron FFs.

Residual effects are sizable for heavy quark FFs and tagged cross sections.

The analysis improves the precision of fragmentation function extractions.

Abstract

In this paper, we present an extraction of the contribution from the "{\it residual}" light charged hadrons to the inclusive unidentified light charged hadron fragmentation functions (FFs) at next-to-leading (NLO) and, for the first time, at next-to-next-to-leading order (NNLO) accuracy in perturbative QCD. Considering the contributions from charged pion, kaon and (anti)proton FFs from recent {\tt NNFF1.0} analysis of charged hadron FFs, we determine the small but efficient {\it residual} charged hadron FFs from QCD analysis of all available single inclusive unidentified charged hadron data sets in electron-positron ($e^+ e^-$) annihilations. The zero-mass variable flavor number scheme (ZM-VFNS) has been applied to account the heavy flavor contributions. The obtained optimum set of {\it residual} charged hadron FFs is accompanied by the well-known Hessian technique to assess the uncertainties in the extraction of these new sets of FFs. It is shown that the {\it residual} contributions of charged hadron FFs have very important impact on the inclusive charged hadron FFs and substantially on the quality and the reliability of the QCD fit. Furthermore, this study shows that the {\it residual} contributions become also sizable for the case of heavy quark FFs as well as for the $c$- and $b$-tagged cross sections.