The non-singlet kaon fragmentation function from e^+e^- kaon production

TL;DR

This paper determines the non-singlet kaon fragmentation function from e+e- data in a model-independent way, including low momentum fractions, and performs the first NNLO fit revealing significant differences from previous analyses.

Contribution

It introduces a model-independent extraction of the non-singlet kaon fragmentation function, incorporating low z data and performing the first NNLO fit.

Findings

Non-singlet kaon fragmentation function is larger at high z than previous results.

Significant differences at low z compared to earlier analyses.

First NNLO fit of kaon fragmentation functions.

Abstract

We perform fits to the available charged and neutral kaon production data in $e^++e^-\to K+X$, $K=K^\pm and K^0_S$, and determine the non-singlet combination of kaon fragmentation functions $D_u^{K^\pm}-D_d^{K^\pm}$ in a model independent way and without any correlations to the other fragmentation functions. Only nuclear isospin invariance is assumed. Working with non-singlets allows us to include the data at very low momentum fractions, which have so far been excluded in global fits, and to perform a first NNLO fit to fragmentation functions. We find that the kaon non-singlet fragmentation function at large $z$ is larger than that obtained by the other collaborations from global fit analysis and differs significantly at low $z$.