Single leptoquark production at high-energy e+e- colliders. C.G. Papadopoulos.

PROGRAM SUMMARY
Title of program: ERATO-LQ
Catalogue identifier: ADKD
Ref. in CPC: 118(1999)81
Distribution format: uuencoded compressed tar file
Operating system: UNIX
Number of lines in distributed program, including test data, etc: 7568
Programming language used: Fortran
Computer: HP

Nature of physical problem:
Leptoquark states emerge in several theoretical frameworks, including the Pati-Salam model, the MSSM, and composite models of quarks and leptons. Leptoquark states coupled to the first generation leptons and quarks can be studied in e+e- colliders. The dominant mode, for leptoquark masses close to the energy threshold, is the single leptoquark production. Leptoquarks can be studied by selecting events with leptons and jets and by investigating the invariant mass distribution of the lepton plus jet system.

Method of solution
Based on the four-fermion event generator ERATO, we have included all possible leptoquark contributions to the processes: e-e+ -> l-l+qqbar and e-e+ -> l- nubarl qqbar'. All tree-order Feynaman graphs as well as all necessary phase space mappings have been calculated and incorporated in the present extension ERATO-LQ. Moreover interference terms with the tree-order SM contributions have been fully included. The decay of the leptoquarks has been treated exactly. An additional code providing the total cross section in the resolved photon approximation has also been included.