Measurement of the Lambda polarization in nu(mu) charged current interactions in the NOMAD experiment

Authors
Astier, P Autiero, D Baldisseri, A Baldo-Ceolin, M Banner, M Bassompierre, G Benslama, K Besson, N Bird, I Blumenfeld, B Bobisut, F Bouchez, J Boyd, S Bueno, A Bunyatov, S Camilleri, L Cardini, A Cattaneo, PW Cavasinni, V Cervera-Villanueva, A Chukanov, A Collazuol, G Conforto, G Conta, C Contalbrigo, M Cousins, R Daniels, D Degaudenzi, H Del Prete, T De Santo, A Dignan, T Di Lella, L Silva, EDE Dumarchez, J Ellis, M Fazio, T Feldman, GJ Ferrari, R Ferrere, D Flaminio, V Fraternali, M Gaillard, JM Gangler, E Geiser, A Geppert, D Gibin, D Gninenko, S Godley, A Gomez-Cadenas, JJ Gosset, J Gossling, C Gouanere, M Grant, A Graziani, G Guglielmi, A Hagner, C Hernando, J Hubbard, D Hurst, P Hyett, N Iacopini, E Joseph, C Juget, F Kirsanov, M Klimov, O Kokkonen, J Kovzelev, A Krasnoperov, A Kustov, D Kuznetsov, V Lacaprara, S Lachaud, C Lakic, B Lanza, A La Rotonda, L Laveder, M Letessier-Selvon, A Levy, JM Linssen, L Ljubicic, A Long, J Lupi, A Marchionni, A Martelli, F Mechain, X Mendiburu, JP Meyer, JP Mezzetto, M Mishra, SR Moorhead, GF Naumov, D Nedelec, P Nefedov, Y Nguyen-Mau, C Orestano, D Pastore, F Peak, LS Pannacchio, E Pessard, H Petti, R Placci, A Polesello, G Pollmann, D Polyarush, A Popov, B Poulsen, C Rathouit, P Rico, J Riemann, P Roda, C Rubbia, A Salvatore, F Schahmaneche, K Schmidt, B Schmidt, T Sevior, M Sillou, D Soler, FJP Sozzi, G Steele, D Stiegler, U Stipcevic, M Stolarczyk, T Tareb-Reyes, M Taylor, GN Tereshchenko, V Toropin, A Touchard, AM Tovey, SN Tran, MT Tsesmelis, E Ulrichs, J Vacavant, L Valdata-Nappi, M Valuev, V Vannucci, F Varvell, KE Veltri, M Vercesi, V Vieira, JM Vinogradova, T Weber, FV Weisse, T Wilson, FF Winton, LJ Yabsley, BD Zaccone, H Zuber, K Zuccon, P
Citation
P. Astier et al., Measurement of the Lambda polarization in nu(mu) charged current interactions in the NOMAD experiment, NUCL PHYS B, 588(1-2), 2000, pp. 3-36
Citations number
62
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
NUCLEAR PHYSICS B
ISSN journal
0550-3213 → ACNP
Volume
588
Issue
1-2
Year of publication
2000
Pages
3 - 36
Database
ISI
SICI code
0550-3213(20001106)588:1-2<3:MOTLPI>2.0.ZU;2-3
Abstract
The Lambda polarization in upsilon (mu) charged current interactions has be en measured in the NOMAD experiment. The event sample (8087 reconstructed L ambda 's) is more than an order of magnitude larger than that of previous b ubble chamber experiments, while the quality of event reconstruction is com parable. We observe negative polarization along the W-boson direction which is enhanced in the target fragmentation region: P-x(x(F) < 0) = -0.21 +/- 0.04(stat) +/- 0.02(sys). In the current fragmentation region we find P-x(x (F) > 0) = -0.09 +/- 0.06(stat) +/- 0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin t ransfer mechanisms. A significant transverse polarization tin the direction orthogonal to the Lambda production plane! has been observed for the first time in a neutrino experiment: P-y = -0.22 +/- 0.03(stat) +/- 0.01(sys). T he dependence of the absolute value of P-y on the Lambda transverse momentu m with respect to the hadronic jet direction is in qualitative agreement wi th the resuits from unpolarized hadron-hadron experiments. (C) 2000 Elsevie r Science B.V. All rights reserved.