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

Abstract

We perform fits to the available charged and neutral kaon production data in $e^{+}+e^{-}\to K+X$, $K=K^{\pm }and{K}_S^0$, 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 $z$.