Probing Quark Fragmentation Functions for Spin-1/2 Baryon Production in   Unpolarized $e^+e^-$ Annihilation
  We study the measurement of the quark fragmentation functions for spin-1/2 baryon production ($\Lambda$ and $\bar \Lambda$, in particular) in unpolarized $e^+e^-$ annihilation. The spin-dependent fragmentation functions $\hat g_1(z)$ and $\hat h_1(z)$ can be probed in the process as a result of quark-antiquark spin correlation and the weak decay of the baryons. The relevant cross section is expressed as a product of the two-jet cross-section, the fragmentation functions, and the differential width of the hyperon decay. 
Kun Chen, Gary R. Goldstein, R. L. Jaffe, and Xiangdong Ji