\title{light quark and spin dependent fragmentation functions at Belle}
\author{R.Seidl for the Belle collaboration}
\institute{Riken Brookhaven Research Center}
The Belle experiment \cite{belledetector} at the asymmetric $e^+e^-$ collider KEKB \cite{kekb} has taken a large amount of data which can be used for the study of fragmentation functions. In particular the more than 60 fb $^{-1}$ of continuum data contain only udsc quark-antiquark pairs and no B meson decays. 
In leading order the normalized yield of inclusive, identified hadrons can be directly related to the sum of fragmentation functions of all accessible quarks and antiquarks. With the statistics available systematic uncertainties will be dominating. While the momentum scale and smearing and very well understood the amount of misidentified hadrons has to be corrected. For this purpose particles where the type of the final state particles is known from the decay $D^*,\Lambda$ are used to obtain the particle detection efficiencies and fake rates. Results on the unpolarized fragmentation functions are expected soon.\\
A second type of fragmentation functions studied in Belle treats the fragmention of transversely polarized quarks. The most prominent of these fragmentation functions is the Collins function \cite{collins2}. Nonzero results from a 29 fb$^{-1}$ continuum data sample have been published \cite{beleprl}. The statistics of these results have been increased by nearly a factor of 20 as for these measurements also the data taken under the $\Upsilon(4S)$ could be included due to a vanishing B-meson background in this analysis. \\
A global analysis of the published Belle Collins asymmetries and the semi-inclusive DIS results from HERMES \cite{hermesprl} and CMPASS \cite{compassprl} containing the Collins effect in conjuction with the quark transversity distribution were successfully performed by Anselmino and collaborators \cite{alexei}. The obtained transversity distribution seems to be smaller than expected from bounds and the Lattice predictions. However many aspects, such as the evolution of the Collins function are still open questions. \\
Another spin dependent fragmentation function, the interference fragmentation function is also being studied at Belle and results are expected soon. 

\begin{thebibliography}{18}

\bibitem{kekb}
S.~Kurokawa,
E.~Kikutani,
Nucl. Instrum. Meth. A{\bf 499},(2003) 1
and other papers included in this volume.

\bibitem{belledetector}
A.~Abashian {\it et~al. }[Belle Collaboration],
Nucl. Instrum. Meth. A, {\bf 479}(2002) 117.


\bibitem{collins2}
J.~C.~Collins,
Nucl. Phys. B{\bf 396}(1993)161.


\bibitem{belleprl}
R.~Seidl {\it et~al.}(Belle Collaboration),
Phys. Rev. Lett. {\bf 96}(2006)232002.


\bibitem{hermesprl}
A.~Airapetian {\it et~al.} [HERMES Collaboration],
Phys. Rev. Lett.{\bf 94},(2005)012002.

 \bibitem{compassprl}
E.S~Ageev {\it et al.} [COMPASS Collaboration],
Nucl.\ Phys.\  B {\bf 765}, 31 (2007)

\bibitem{alexei}
  M.~Anselmino, M.~Boglione, U.~D'Alesio, A.~Kotzinian, F.~Murgia, A.~Prokudin and C.~Turk,
  Phys.\ Rev.\  D {\bf 75} (2007) 054032
\end{thebibliography}
