Matching NLO QCD computations with parton shower simulations: the POWHEG method

The aim of this work is to describe in detail the POWHEG method, first suggested by one of the authors, for interfacing parton-shower generators with NLO QCD computations. We describe the method in its full generality, and then specify its features in two subtraction frameworks for NLO calculations: the Catani-Seymour and the Frixione-Kunszt-Signer approach. Two examples are discussed in detail in both approaches: the production of hadrons in e(+)e(-) collisions, and the Drell-Yan vector-boson production in hadronic collisions.