Measurement of the W mass and width in e+e- collisions at 189 GeV

R. Barate, D. Decamp, P. Ghez, C. Goy, S. Jezequel, J. P. Lees, F. Martin, E. Merle, M. N. Minard, B. Pietrzyk, R. Alemany, S. Bravo, M. P. Casado, M. Chmeissani, J. M. Crespo, E. Fernandez, M. Fernandez-Bosman, L. Garrido, E. Graugés, M. MartinezG. Merino, R. Miquel, L. M. Mir, A. Pacheco, H. Ruiz, A. Colaleo, D. Creanza, M. de Palma, G. Iaselli, G. Maggi, M. Maggi, S. Nuzzo, A. Ranieri, G. Raso, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, A. Tricomi, G. Zito, X. Huang, J. Lin, Q. Ouyang, T. Wang, Y. Xie, R. Xu, S. Xue, J. Zhang, L. Zhang, W. Zhao, D. Abbaneo, G. Boix, O. Buchmüller, M. Cattaneo, F. Cerutti, G. Dissertori, H. Drevermann, R. W. Forty, M. Frank, F. Gianotti, T. C. Greening, A. W. Halley, J. B. Hansen, J. Harvey, P. Janot, B. Jost, M. Kado, V. Lemaitre, P. Maley, P. Mato, A. Minten, A. Moutoussi, F. Ranjard, L. Rolandi, D. Schlatter, M. Schmitt, O. Schneider, P. Spagnolo, W. Tejessy, F. Teubert, E. Tournefier, A. Valassi, J. J. Ward, A. E. Wright, Z. Ajaltouni, F. Badaud, G. Chazelle, O. Deschamps, S. Dessagne, A. Falvard, P. Gay, C. Guicheney, P. Henrard, J. Jousset, B. Michel, S. Monteil, J. C. Montret, D. Pallin, J. M. Pascolo, P. Perret

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The mass of the W boson is determined in e+e- collisions at LEP by the direct reconstruction of W decays in WW → qq̄qq̄ and WW → ℓvqq̄ events, supplemented by measurements using the kinematic properties of the leptons in the WW → ℓvℓv decay channel. The main sample of W pairs is selected from an integrated luminosity of 174 pb-1 collected with the ALEPH detector in 1998 at a centre-of-mass energy of 188.63 GeV. The combined result from all channels is mW = 80.432 ± 0.072(stat.) ± 0.041(syst.) ± 0.019(FSI) ± 0.017(LEP) GeV/c2, where FSI represents the possible effects of final state interactions in the qq̄qq̄ channel. In a second two-parameter fit to the qq̄qq̄, evqq̄ and μvqq̄ channels, where the W mass and width are decoupled, the average W width is found to be 2.24 ± 0.20(stat.) ± 0.13(syst.) GeV/c2, consistent with the Standard Model prediction. The combination of the mass measurement presented in this paper together with those derived previously from the W pair cross section at 161 and 172GeV and direct reconstruction at 172 and 183 GeV gives mW = 80.418 ± 0.061(stat.) ± 0.040(syst.) ± 0.019(FSI) ± 0.017(LEP) GeV/c2.
Original languageEnglish
Pages (from-to)241-261
JournalEuropean Physical Journal C
Issue number2
Publication statusPublished - 1 Jan 2000

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    Barate, R., Decamp, D., Ghez, P., Goy, C., Jezequel, S., Lees, J. P., Martin, F., Merle, E., Minard, M. N., Pietrzyk, B., Alemany, R., Bravo, S., Casado, M. P., Chmeissani, M., Crespo, J. M., Fernandez, E., Fernandez-Bosman, M., Garrido, L., Graugés, E., ... Perret, P. (2000). Measurement of the W mass and width in e+e- collisions at 189 GeV. European Physical Journal C, 17(2), 241-261.