A general derivation of differential cross section in quark-quark   scatterings at fixed impact parameter
  We propose a general derivation of differential cross section in quark-quark scatterings at fixed impact parameters. The derivation is well defined and free of ambiguity in the conventional one. The approach can be applied to a variety of partonic and hadronic scatterings in low or high energy particle collisions. 
Shou-wan Chen, Jian Deng, Jian-hua Gao, Qun Wang