PROJET - JET CROSS-SECTIONS IN DEEPLY INELASTIC ELECTRON-PROTON SCATTERING - VERSION-4.1

PROJET is a parton level Monte Carlo program for the calculation of je t cross sections in deeply inelastic electron proton scattering. In it s present version it contains the Born level diagrams for the producti on of (1+1), (2+1) and (3+1) jets and the next-to-leading order correc tions for the production cross sections of (1+1) and (2+1) jets for al l polarisations of the exchanged virtual photon. In particular, the fu ll angular correlations between the lepton and jet momenta are impleme nted. The program permits the application of acceptance cuts on all ex ternal momenta. For this purpose, the program creates an event record accessible to the user program with all momenta in the laboratory fram e and in the center of momentum frame of the proton and the virtual ph oton. This option is indispensable for phenomenological studies becaus e of the strong dependence of cross sections on phase space restrictio ns and the large uncertainty of fragmentation corrections in the proto n direction. Since PROJET uses the Monte Carlo integration method for the evaluation of phase space integrals, the weights of the generated events can be used to produce distributions of observables related to jet momenta.