NNLO QCD calculation of hadron multiplicities in light-quark jets at lepton colliders

TL;DR

This paper calculates NNLO QCD corrections to hadron multiplicities in light-quark jets at lepton colliders using the P2B method, providing precise predictions and comparing them with experimental data to improve fragmentation function determinations.

Contribution

The paper introduces a NNLO QCD calculation for hadron multiplicities in light-quark jets using the P2B method, validated against NLO results and applied to experimental data.

Findings

NNLO predictions for $D_{K^{-}}$ asymmetry are presented.

Comparison with SLD data shows a suppression in intermediate $z_h$ range.

Incorporating data can improve fragmentation function fits.

Abstract

We present the calculation of next-to-next-to-leading-order (NNLO) QCD corrections to hadron multiplicities in light-quark jets at lepton colliders, employing the ``projection-to-Born" (P2B) method implemented in the FMNLO program. Taking the next-to-leading-order result as an example, we rigorously establish the validity of our P2B-based calculation. We then present NNLO predictions for the normalized asymmetry $D_{K^{-}}$ between hadron and antihadron production in light-quark jets and compare them with SLD data. We find that a suppression of these SLD measurements relative to NPC23 predictions for $D_{K^{-}}$ emerges in the intermediate $z_h$ domain ($0.2 \lesssim z_h \lesssim 0.7$). We expect that incorporating these SLD data into global QCD fits will enable improved determination of fragmentation functions.