Investigation of the factorization scheme dependence of finite order   perturbative QCD calculations: searching for approximately ZERO factorization   scheme
  The possibility of an improvement of current NLO Monte Carlo event generators by means of choosing a suitable factorization scheme is studied. The optimal factorization scheme for combining initial state parton showers and NLO hard scattering cross-sections is the ZERO factorization scheme, in which all NLO splitting functions vanish. However, it has turned out that the ZERO factorization scheme has a limited range of practical applicability. Hence, this paper is focused on searching for a factorization scheme which is applicable at the NLO in the full range of x relevant for QCD phenomenology and simultaneously close to the ZERO factorization scheme (i.e. the corresponding NLO splitting functions are close to zero). 
Karel Kolar
hep-ph hep-th