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Ancu, L S; Anderson, S; Arov, M; Asman, B; Autermann, C; Banerjee, S; Barberis, E; Bellavance, A; Bezzubov, V A; Buchanan, N J; Cammin, J; Chakraborty, D; Chan, K M; Chandra, A; Cwiok, M; Demarteau, M; Diehl, H T; Diesburg, M; Ermolov, P; Evdokimov, V N; Fuess, S; Greenlee, H; Gris, Ph; Grivaz, J-F; Guo, J; Gutierrez, G; Hall, R E; Hauptman, J M; Heintz, U; Hensel, C; Hirosky, R; Houben, P; Hynek, V; Jarvis, C; Johnson, M; Jonckheere, A; Jonsson, P; Kajfasz, E; Kalk, J R; Kappler, S; Kasper, P A; Kirsch, M; Kunori, S; Kupco, A; Kvita, J; Lam, D; Lebrun, P; Leflat, A; Li, L; Lipton, R; Liu, Z; Lubatti, H J; Mackin, D; Madaras, R J; Magass, C; Mal, P K; Martin, B; Mulhearn, M; Mundim, L; Negret, J P; O'Neil, D C; Park, S-J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Piegaia, R; Piper, J; Podstavkov, V M; Potter, C; Prado da Silva, W L; Renkel, P; Rizatdinova, F; Robinson, S; Rominsky, M; Ruchti, R; Safronov, G; Santoro, A; Schellman, H; Schwartzman, A; Sirotenko, V; Skubic, P; Sopczak, A; Strang, M A; Strauss, M; Svoisky, P; Tanasijczuk, A; Tissandier, F; Trefzger, T; Tuchming, B; Unalan, R; Uvarov, S; Uvarov, L; Van Kooten, R; Vaupel, M; Wayne, M; Wyatt, T R; Yan, M; Zverev, E G
Physical review letters, 02/2008, Letnik: 100, Številka: 6Journal Article
We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb(-1) sample of candidate tt events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron pp Collider. We reconstruct the angle theta(*) between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting costheta(*) distribution finds that the fraction of longitudinal W bosons f(0)=0.425+/-0.166(stat)+/-0.102(syst) and the fraction of right-handed W bosons f(+)=0.119+/-0.090(stat)+/-0.053(syst), which is consistent at the 30% C.L. with the standard model.
