GRAPE-Dilepton (version 1.1) a generator for dilepton production in ep collisions. T. Abe.

PROGRAM SUMMARY
Title of program: GRAPE-Dilepton (v1.1)
Catalogue identifier: ADNR
Ref. in CPC: 136(2001)126
Distribution format: tar gzip file
Operating system: UNIX
High speed store required: 9MK words
Number of lines in distributed program, including test data, etc: 262390
Keywords: Elementary particle physics, QCD, Dilepton, Lepton-pair, ep collision, Bethe-Heitler, Z boson, Dipole form factor, Hadron tensor, Lepton tensor, Structure function, Parton density, GRACE.
Programming language used: Fortran

Nature of problem:
A precise estimation of the cross-section of the electroweak dilepton production in ep collisions is required in various physics analyses, where 8~48 Feynman diagrams can contribute.

Method of solution:
The automatic calculation system GRACE is used to obtain all of the relevant helicity amplitudes. The phase space is divided into the 3 regions according to the kinematics at the proton vertex, and the 3 different calculation methods are applied. The radiative corrections are included using the structure function and the parton shower methods.

Restrictions:
Higgs, the proton-Z0 coupling and lepton-pair production through photon radiation from the proton are not included. The contribution from the resolved photon, i.e. Drell-Yan process in ep collisions is not included.

Typical running time:
1 hour for a cross-section integration and 1 msec per 1 event for an event generation.