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Manuscript Title: WEXTER and ERAFITTER: two programs to fit MW at LEP2 using the best measurable kinematical variables.
Authors: F.A. Berends, C.G. Papadopoulos, R. Pittau
Program title: WEXTER and ERAFITTER
Catalogue identifier: ADJJ_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 115(1998)32
Programming language: Fortran.
Computer: SUN workstation.
Operating system: UNIX.
Keywords: Particle physics, Elementary, Event reconstruction, Fit to mw at lep2, Direct reconstruction, Method, Best measurable, Kinematical variables, Maximum likelihood fit.
Classification: 11.9.

Nature of problem:
The extraction of MW from the LEP2 data.

Solution method:
The direct fit method is used, in which the theoretical probabilities of observing the final-state kinematical configurations are computed by integrating over the quantities that are not well measured. Therefore, an event-by-event kinematical reconstruction is avoided. MW is then determined through a maximum likelihood fit.

Restrictions:
The jets are treated at the partonic level.

Running time:
WEXTER: about 90 seconds on a SUN workstation to fit 10 semileptonic data points (case 2 in the text) using 7 values of MW and 2000 Monte Carlo points per event per mass, ISR included.
ERAFITTER: for the same case as before, about 28 seconds on HP/712 to fit 10 data points, using 9 values of MW and 100 Monte Carlo points per event per mass.

References:
[1] F.A. Berends, C.G. Papadopoulos and R. Pittau, Phys. Lett. B417 (1998) 385.