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Manuscript Title: Monte Carlo program BHLUMI 2.01 For Bhabha scattering at low angles with Yennie-Frautschi-Suura exponentiation.
Authors: S. Jadach, E. Richter-Was, B.F.L. Ward, Z. Was
Program title: BHLUMI version 2.01
Catalogue identifier: ACHI_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 70(1992)305
Programming language: Fortran.
Computer: IBM 3090.
Operating system: VM/CMS.
RAM: 45K words
Word size: 32
Keywords: Radiative corrections, Monte carlo simulation, Bhabha scattering, Bremsstrahlung, Quantum electrodynamics (qed), Electroweak theory, Structure functions, Particle physics, Elementary.
Classification: 11.4.

Nature of problem:
Small-angle Bhabha scattering process is used in all electron-positron colliders to calculate machine luminosity. This process is subject to QED radiative corrections which has to be known for arbitrary cut-offs and/or acceptance with precision at least factor three better than pure experimental precision. It means that the level of 0.2 per cent should be reached. The realistic simulation should include multiple emission of the bremsstrahlung photons.

Solution method:
The Monte Carlo simulation of the small-angle process is an ideal solution. It provides integrated cross-section for arbitrary cuts. Direct simulation of the final-state electrons and photos is precisely what is needed for detector simulation purpose.

The overall precision of the QED calculation is restricted, for typical LEP/SLC luminosity angular range, to 0.25 per cent.

Running time:
Efficiency for multiphoton sub-generator is 276 constant weight events and 756 variable weight events per one IBM 3090 CPU second.