Global analysis of hadron-production data in e^+ e^- annihilation for determining fragmentation functions

Fragmentation functions of pion, kaon, and nucleon are determined by global analyses of hadron-production data in $e^+e^-$ annihilation. It is particularly important that uncertainties of the fragmentation functions are estimated for the first time. We found that light-quark and gluon fragmentation functions have large uncertainties, so that one should be careful in using these functions for hadron-production processes in heavy-ion collisions and lepton scattering. The analysis is extended to possible exotic hadron search by fragmentation functions. We found that internal structure of $f_0 (980)$, such as $s\bar s$ or tetraquark configuration, can be determined by noting differences between favored and disfavored fragmentation functions.