Subtraction method for NLO corrections in Monte-Carlo event generators forZ boson production

We use a subtraction method to construct NLO corrections in a Monte-Carlo e vent generator for the case of vector boson production in Drell-Yan process es. Our calculations are carried out both for the Bengtsson-Sjostrand-van Z ijl (BSZ) algorithm and for a modified algorithm proposed by Collins. In th e case of the modified algorithm, we compute the relation between the parto n distribution functions and the ones in the (MS) over bar scheme; this rel ation is the same as the corresponding relation for DIS. For the BSZ algori thm, we show that there is no simple relation.