. Le-système-d, injection du LEP L'obtention des faisceaux e + e ? , avec desénergiesélevéesdesénergiesdesénergiesélevées, exige l'utilisation d'une cha??necha??ne complexe d'injection (voir figure 2.1) qui tire parti des différents accélérateurs existants au CERN : le Super Proton Synchrotron (SPS), le Proton Synchrotron (PS)

. Le-faisceau-d-'´-electrons, LesélectronsLesélectrons sont envoyés sur une cible de tungstène o` u des pairesélectronpairesélectron-positron sont créées LesélectronsLesélectrons et les positrons sont ensuite guidés vers le LINAC, o` u ils sont accélérés jusqu'` a uné energie de 600 MeV. Ces paquets de particules sont accumulés dans l'Electron Positron Accumulator (EPA) avant d'? etre injectés dans les machines suivantes. D` es que le nombre de particules dans l'EPA est suffisant, les paquets sont envoyés dans le PS o` u ils subissent une accélération jusqu'` a 3.5 GeV. La phase suivante consistè a introduire les faisceaux e + e ? dans le pas utilisé pour estimer l'incertitude systématique. Dans ces modèles, la probabilité de recombinaison de couleur est maximal pour la configuration correspondantàcorrespondant`correspondantà des " longueurs

. Geiger, Le modèle EG ne reproduit pas les multiplicités des particules observées dans les données expérimentales et il est désormais abandonné. Le modèle SK est fondé sur le modèle des cordes de Lund dans lequel des cordes entre les partons des deux W se croisent. La probabilité de recombinaison de couleur est proportionnelle au volume d'espace temps lors du croisement de ces " tubes de couleur " . Les deux principaux scénario sont appelés SKI et SKII et feront l

. Dans-cette-transition, les interactions dans l'´ etat final perturbent la détermination de la masse du top, qui est l'un des objectifs principaux des futurs

D. Collab, Measurement of the mass of the W boson using direct reconstruction at 183 GeV, (Publication), to be submitted in Phys, Lett. B, 1999.

S. L. Glashow, Partial-symmetries of weak interactions, Nuclear Physics, vol.22, issue.4, 1961.
DOI : 10.1016/0029-5582(61)90469-2

S. Weinberg, A Model of Leptons, Physical Review Letters, vol.19, issue.21, p.1264, 1967.
DOI : 10.1103/PhysRevLett.19.1264

A. Salam, The Theory of Elementary Particles, Nobel Symposium n o 8 (N. Svartholm Almqvist and Wiksell, 1968.
DOI : 10.2307/3614805

M. Acciarri, The L3 silicon microvertex detector, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol.351, issue.2-3, p.300, 1994.
DOI : 10.1016/0168-9002(94)91357-9
URL : http://cds.cern.ch/record/267525/files/ppe-94-122.pdf

M. Chemarin, Test beam results for an upgraded forward tagger of the L3 experiment at LEP II, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol.349, issue.2-3, p.345, 1994.
DOI : 10.1016/0168-9002(94)91198-3
URL : https://hal.archives-ouvertes.fr/in2p3-00007580

A. Adam, The forward muon detector of L3, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol.383, issue.2-3, pp.342-366, 1996.
DOI : 10.1016/S0168-9002(96)00777-2

J. Kneur, La théorié electrofaible au LEP2, cours donnédonnéà la 28èmé28èmé ecole de Gif-sur-Yvette, 9-13 Septembre, 1996.

M. Davier and L. , interactionélectrofaibleinteractionélectrofaible : un bilan des résultats de LEP1 et SLC, 21 janvier 1998, cours donnédonnéà la 28èmé28èmé ecole de Gif-sur-Yvette, pp.9-13, 1996.

T. P. Cheng and L. F. Li, Gauge theory of elementary particle physics, Clarendon press-Oxford, 1984.

L. H. Ryder, Quantum field theory, 1985.
DOI : 10.1017/CBO9780511813900

P. Bhat, H. Prosper, and S. Snyder, Top Quark Physics at the Tevatron, hep-ex, J. Mod. Phys. A, vol.9809011, 1998.

T. Kajita, Super-Kamiokande Coll., Talk presented at Neutrino '98, 1998.

Y. Fukuda, Evidence for Oscillation of Atmospheric Neutrinos, Physical Review Letters, vol.81, issue.8, p.1562, 1998.
DOI : 10.1103/PhysRevLett.81.1562

T. Maskawa and M. Kobayashi, CP-Violation in the Renormalizable Theory of Weak Interaction, Prog. Th. Phys, vol.652, p.49, 1973.

A. Sirlin, theory: A simple renormalization framework, Physical Review D, vol.22, issue.4, p.971, 1980.
DOI : 10.1103/PhysRevD.22.971

J. H. Kühn and M. Steinhauser, A theory driven analysis of the effective QED coupling at M Z , hep-ph/9802241, Phys. Lett. B, vol.429, issue.158, 1998.

M. Davier and A. Höcker, Improved determination of ??(MZ2) and the anomalous magnetic moment of the muon, Physics Letters B, vol.419, issue.1-4, p.419, 1998.
DOI : 10.1016/S0370-2693(97)01512-8

G. Quast, talk given at the EPS HEP Conference, pp.97-157, 1997.

P. Gambino, Precision tests of the Standard Model : higher order corrections and the Higgs mass, hep-ph/9812332, Symposium on Radiative Corrections (RADCOR 98), pp.8-12, 1998.

G. Weiglein, Results for Precision Observables in the Electroweak Standard Model at Two-Loop Order and Beyond, KA-TP-22-1998, hep-ph/9901317,KA-TP-11-1998, hep-ph, Acta Phys. Pol. B, vol.9807222, issue.10, 1998.

F. Teubert, Precision test of the Standard Model from Z physics, Invited talk presented at the IVth International Symposium on Radiative Corrections (RADCOR 98), p.9811414, 1998.

D. Collab and P. Abreu, W pair production cross-section and W branching ratios in e + e ? interactions at 183 GeV, Accepted by Phys, Lett. B, pp.99-146

S. Dittmaier, Radiative corrections to W-pair production in e + e ? annihilation, Invited talk presented at the IVth International Symposium on Radiative Corrections (RADCOR 98), p.9811434, 1998.

W. Beenakker, A. Denner, S. Dittmaier, J. Hoogland, R. Kleiss et al., The fermion-loop scheme for finite-width effects in e+et- annihilation into four fermions, Nuclear Physics B, vol.500, issue.1-3, pp.96-127, 1996.
DOI : 10.1016/S0550-3213(97)00316-7

W. Beenakker, F. A. Berends, and A. P. Chapovsky, Radiative corrections to pair production of unstable particles: Results for E+E??? ??? 4 fermions, Nuclear Physics B, vol.548, issue.1-3, p.9811481, 1998.
DOI : 10.1016/S0550-3213(99)00110-8

L. Taylor, Properties of the W Boson, Proceedings of the XVIIth International Conference on Physics in Collision, 1997.

T. Muta, R. Najima, and S. Wakaizumi, Effects of the W-boson width in e + e ? ? W + W ? reactions, Mod, Phys. Lett. A, vol.1, issue.203, 1986.

M. Böhm, Electroweak radiative corrections to e+e??? ??? W+W???, Nuclear Physics B, vol.304, p.463, 1988.
DOI : 10.1016/0550-3213(88)90638-4

W. Beenakker and A. Denner, Radiative corrections to off-shell gauge-boson pair production, Zeuthen Workshop on Elementary-particle Physics : Loops and Legs in Gauge Theories Rheinsberg, Proceedings T Riemann and J Blmlein Acta Phys. Pol. B, vol.29, issue.10, pp.19-24, 1998.

S. Dittmaier, Theoretical aspects of W-pair production in e + e ? collisions, 3rd International Symposium on Radiative Corrections -CRAD '96

S. Jadach, W. Placzek, M. Skrzypek, B. F. Ward, and Z. Was, Monte Carlo program KoralW 1.42 for all four-fermion final states in e+e??? collisions, Computer Physics Communications, vol.119, issue.2-3, pp.98-0702, 1998.
DOI : 10.1016/S0010-4655(99)00219-2

A. Sommerfeld, Atombau und Spektrallinien Bd, 1939.

S. Myers, The LEP Collider, from design to approval and commissioning, 1991.

P. Delphi-collaboration and . Abreu, Performance of the DELPHI detector, Nucl. Instrum. Methods A, vol.378, issue.57, 1996.

M. Delsim-user, DELSIM Reference Manual, DELPHI 87-98/PROG 100, pp.87-96, 1989.

A. Ballestrero, V. A. Khoze, E. Maina, S. Moretti, and W. J. Stirling, Perturbative rates and colour rearrangement effects in four-jet events at LEP2, Cavendish-HEP-95, 1996.

G. V. Borisov and C. Mariotti, Performance of b-tagging at LEP, pp.97-113, 1997.

D. Collab and P. Abreu, Measurement of the W-pair cross-section and of the W mass in e + e ? interactions at 172 GeV, Eur. Phys. J. C, vol.2, p.581, 1991.

T. Sjöstrand, Pythia 5.7 and Jetset 7.4, Physics and Manual, Comput. Phys. Commun, vol.82, issue.74, 1994.

I. Knowles and G. D. Lafferty, Hadronization in decay, Journal of Physics G: Nuclear and Particle Physics, vol.23, issue.7, pp.731-789, 1997.
DOI : 10.1088/0954-3899/23/7/003

A. J. Buras and R. Fleischer, Quark Mixing, CP Violation and Rare Decays After the Top Quark Discovery, Heavy Flavours II, p.9704376, 1997.
DOI : 10.1142/9789812812667_0002

X. Artru and G. Mennessier, String model and multiproduction, Nuclear Physics B, vol.70, issue.1, pp.93-115, 1974.
DOI : 10.1016/0550-3213(74)90360-5
URL : http://doi.org/10.1016/0550-3213(74)90360-5

B. Anderson, G. Gustafson, and C. Peterson, A semiclassical model for quark jet fragmentation, Zeitschrift f???r Physik C Particles and Fields, vol.70, issue.1, pp.105-116, 1979.
DOI : 10.1007/BF01450386

B. Anderson, G. Gustafson, T. Sjöstrand, and Z. , A three-dimensional model for quark and gluon jets, Zeitschrift f??r Physik C Particles and Fields, vol.135, issue.3, pp.235-240, 1980.
DOI : 10.1007/BF01557774

B. Anderson, G. Gustafson, G. Ingelman, and T. Sjöstrand, Parton fragmentation and string dynamics, Physics Reports, vol.97, issue.2-3, pp.31-145, 1983.
DOI : 10.1016/0370-1573(83)90080-7

B. Anderson, G. Gustafson, B. Söderberg, and Z. , A general model for jet fragmentation, Zeitschrift f???r Physik C Particles and Fields, vol.49, issue.4, pp.317-329, 1983.
DOI : 10.1007/BF01407824

C. Peterson, D. Schlatter, I. Schmitt, and P. Zerwas, annihilation spectra, Physical Review D, vol.27, issue.1, pp.105-111, 1983.
DOI : 10.1103/PhysRevD.27.105

S. Moretti, L. Lönnblad, and T. Sjöstrand, New and Old Jet Clustering Algorithms for Electron-Positron Events, RAL-TR-98-003, p.9804296

A. Duperrin, W mass reconstruction using MULTIJETS, DELPHI 97-170 PHYS 745

A. Duperrin, Measurement of the W Mass in WW ? q¯ qq¯ q at 183 GeV with neural network

F. Cossuti and A. Ouraou, Reweighting of EXCALIBUR events for 4 fermion physics at LEP200, DELPHI, pp.98-107

R. Moller, Bose-Einstein Corellations in WW Events

V. Kartvelishvili, R. Kvatadze, and R. Møller, Estimating the effects of Bose-Einstein correlations on the W mass measurement at LEP2, Physics Letters B, vol.408, issue.1-4, p.331, 1997.
DOI : 10.1016/S0370-2693(97)00836-8

S. Todorova and J. Rames, IReS 97 PRA-HEP97/16 and hep-ph/9710280, Nucl. Phys. B, vol.29, issue.627, 1998.

P. Delphi-collab and . Abreu, Charged and Identified Particles from the Hadronic Decay of W bosons and in e + e ? ? q¯ q at 183 and 189 GeV, p.12, 1999.

V. A. Khoze, Interconnection phenomena in W + W ? and tt events, 12ème12ème Rencontre de Physique de la Vallée d'Aoste : Results and Perspectives in Particle Physics, Publ. in Proceedings, vol.9805505, pp.hep-ph, 1998.

L. Lönnblad, Reconnecting coloured dipoles, Zeitschrift f??r Physik C: Particles and Fields, vol.63, issue.1, pp.95-218
DOI : 10.1007/s002880050087

D. Collab, Fast simulation

G. Montagna, G. Nicrosini, F. Passarino, and . Piccinini, TOPAZ0 4.0 ??? A new version of a computer program for evaluation of deconvoluted and realistic observables at LEP 1 and LEP 2, Computer Physics Communications, vol.117, issue.3, p.9804211, 1998.
DOI : 10.1016/S0010-4655(98)00080-0

D. Bardin and G. Passarino, Upgrading of Precision Calculations for Electroweak Observables, p.9803425, 1998.

K. Macfarland, talk presented at the XXXIIIth Rencontres de Moriond, pp.15-21, 1998.

M. W. Grünewald, Combined Analysis of Precision Electroweak Results

W. S. Mccullogh and W. Pitts, A logical Calculus of the Ideas Immanent in, Nervous Activity Bull. of Math. Biophysics, vol.5, issue.115, 1943.

D. O. Hebb, The Organization of Behaviour, 1949.

R. Rosenblatt, Principles of Neurodynamics, Spartan Books, 1962.

J. J. Hopfield, Neural Networks and Physical Systems with Emergent Collective Computational Abilities, Proceedings of the National Academy of Sciences, pp.2-554, 1982.

D. E. Rumelhart, Learning representations by back-propagating errors, Nature, vol.85, issue.6088, 1986.
DOI : 10.1038/323533a0

B. Denby, Neural Netwroks and Cellular Automata in Experimental High Energy Physics, Comput. Phys. Commun, pp.49-429, 1988.

C. Peterson, T. Rognvaldsson, and L. Lönnblad, JETNET 3.0???A versatile artificial neural network package, Computer Physics Communications, vol.81, issue.1-2, p.81, 1994.
DOI : 10.1016/0010-4655(94)90120-1