Factorization and transverse momentum for two-hadron production in   inclusive $e^+ e^-$ annihilation
  We study factorization of processes involving two fragmentation functions in the case of very small transverse momenta. We consider two-hadron production in inclusive $e^+ e^-$ annihilation and demonstrate a new simple and illustrative method of factorization for such processes including leading order $\alpha_S$ corrections. 
I.V. Anikin, O.V. Teryaev