Proposal for exotic-hadron search by fragmentation functions

It is proposed that fragmentation functions should be used to identify exotic hadrons. As an example, fragmentation functions of the scalar meson $f_0(980)$ are investigated. It is pointed out that the second moments and functional forms of the $u$- and $s$-quark fragmentation functions can distinguish the tetraquark structure from $q\overline{q}$. By the global analysis of $f_0(980)$ production data in electron-positron annihilation, its fragmentation functions and their uncertainties are determined. It is found that the current available data are not sufficient to determine its internal structure, while precise data in the future should be able to identify exotic quark configurations.