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Manuscript Title: MENLO_PARC, a program for e+e- -> 4 jets at next-to-leading order.
Authors: A. Signer
Program title: MENLO_PARC
Catalogue identifier: ADGS_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 106(1997)125
Programming language: Fortran.
RAM: 1028K words
Keywords: Particle physics, Elementary, Event simulation, Electron-positron, Annihilation, Next-to-leading order, Corrections, Four jet, Subtraction method.
Classification: 11.2.

Nature of problem:
The expansion in the strong coupling constant of any four-jet quantity in electron-positron annihilation starts only at O(alphas**2). As a result, the dependence of the theoretical predictions on the renormalization scale is very large. The only reliable way to reduce this dependence and, therefore, get more precise predictions is to include the full next-to-leading order correction.

Solution method:
Recently, the calculations of the one-loop amplitudes for electron- positron annihilation into four partons have been completed, using the helicity method and colour ordering [1,2]. Since the tree-level amplitudes with five partons in the final state have also been calculated by several groups a few years ago, all amplitudes which contribute to the next-to-leading order cross section are now available. A general version [3] of the subtraction method has been used to cancel the real and virtual singularities for arbitrary four-jet quantities. The integrand has been split into pieces which contain only a very limited number of square root singularities. Each of these contributions can then be reliably integrated.

Running time:
Between hours and months, depending on the nature of the calculation and the desired accuracy of the result.

References:
[1] Z. Bern, L. Dixon and D. Kosower, preprint hep-ph/9708239.
[2] Z. Bern, L. Dixon, D. Kosower and S. Weinzierl, Nucl. Phys. B489 (1997) 3.
[3] S. Frixione, Z. Kunszt and A. Signer, Nucl. Phys. B467 (1996) 399.