ALPGEN, a generator for hard multiparton processes in hadronic collisions

This paper presents a new event generator, ALPGEN, dedicated to the study of multiparton hard processes in hadronic collisions. The code performs, at the leading order in QCD and EW interactions, the calculation of the exact matrix elements for a large set of parton-level processes of interest in the study of the Tevatron and LHC data. The current version of the code describes the following final states: (W->e nu) Q Qbar+ N jets and (Z/gamma* -> l lbar) Q Qbar+N jets (Q being a heavy quark), with N<=4; (W -> e nu) + N jets and (Z/gamma* -> l lbar)+ N jets (N<=6); nW+mZ+lH+N jets, with n+m+l+N<=8 and N<=3; Q Qbar+N jets (N<=6); Q Qbar Q' Qbar'+N jets, with Q and Q' heavy quarks (possibly equal) and N<=4; H Q Qbar+N jets (N<=4). Parton-level events are generated, providing full information on their colour and flavour structure, enabling the evolution of the partons into fully hadronised final states.