Measurement of the average polarization of b baryons in hadronic Z0 decays

G. Abbiendi*, K. Ackerstaff, G. Alexander, J. Allison, N. Altekamp, K. J. Anderson, S. Anderson, S. Arcelli, S. Asai, S. F. Ashby, D. Axen, G. Azuelos, A. H. Ball, E. Barberio, R. J. Barlow, R. Bartoldus, J. R. Batley, S. Baumann, J. Bechtluft, T. BehnkeK. W. Bell, G. Bella, A. Bellerive, S. Bentvelsen, S. Bethke, S. Betts, O. Biebel, A. Biguzzi, S. D. Bird, V. Blobel, I. J. Bloodworth, M. Bobinski, P. Bock, J. Böhme, D. Bonacorsi, M. Boutemeur, S. Braibant, P. Bright-Thomas, L. Brigliadori, R. M. Brown, H. J. Burckhart, C. Burgard, R. Bürgin, P. Capiluppi, R. K. Carnegie, A. A. Carter, J. R. Carter, C. Y. Chang, D. G. Charlton, D. Chrisman, C. Ciocca, P. E.L. Clarke, E. Clay, I. Cohen, J. E. Conboy, O. C. Cooke, C. Couyoumtzelis, R. L. Coxe, M. Cuffiani, S. Dado, G. M. Dallavalle, R. Davis, S. de Jong, L. A. del Pozo, A. de Roeck, K. Desch, B. Dienes, M. S. Dixit, J. Dubbert, E. Duchovni, G. Duckeck, I. P. Duerdoth, D. Eatough, P. G. Estabrooks, E. Etzion, H. G. Evans, F. Fabbri, M. Fanti, A. A. Faust, F. Fiedler, M. Fierro, I. Fleck, R. Folman, A. Fürtjes, D. I. Futyan, P. Gagnon, J. W. Gary, J. Gascon, S. M. Gascon-Shotkin, G. Gaycken, C. Geich-Gimbel, G. Giacomelli, P. Giacomelli, V. Gibson, W. R. Gibson, D. M. Gingrich, D. Glenzinski, J. Goldberg, W. Gorn, C. Grandi, E. Gross, J. Grunhaus, M. Gruwé, G. G. Hanson, M. Hansroul, M. Hapke, K. Harder, C. K. Hargrove, C. Hartmann, M. Hauschild, C. M. Hawkes, R. Hawkings, R. J. Hemingway, M. Herndon, G. Herten, R. D. Heuer, M. D. Hildreth, J. C. Hill, S. J. Hillier, P. R. Hobson, A. Hocker, R. J. Homer, A. K. Honma, D. Horváth, K. R. Hossain, R. Howard, P. Hüntemeyer, P. Igo-Kemenes, D. C. Imrie, K. Ishii, F. R. Jacob, A. Jawahery, H. Jeremie, M. Jimack, C. R. Jones, P. Jovanovic, T. R. Junk, D. Karlen, V. Kartvelishvili, K. Kawagoe, T. Kawamoto, P. I. Kayal, R. K. Keeler, R. G. Kellogg, B. W. Kennedy, A. Klier, S. Kluth, T. Kobayashi, M. Kobel, D. S. Koetke, T. P. Kokott, M. Kolrep, S. Komamiya, R. V. Kowalewski, T. Kress, P. Krieger, J. von Krogh, T. Kuhl, P. Kyberd, G. D. Lafferty, D. Lanske, J. Lauber, S. R. Lautenschlager, I. Lawson, J. G. Layter, D. Lazic, A. M. Lee, D. Lellouch, J. Letts, L. Levinson, R. Liebisch, B. List, C. Littlewood, A. W. Lloyd, S. L. Lloyd, F. K. Loebinger, G. D. Long, M. J. Losty, J. Ludwig, D. Liu, A. Macchiolo, A. Macpherson, W. Mader, M. Mannelli, S. Marcellini, C. Markopoulos, A. J. Martin, J. P. Martin, G. Martinez, T. Mashimo, P. Mättig, W. J. McDonald, J. McKenna, E. A. Mckigney, T. J. McMahon, R. A. McPherson, F. Meijers, S. Menke, F. S. Merritt, H. Mes, J. Meyer, A. Michelini, S. Mihara, G. Mikenberg, D. J. Miller, R. Mir, W. Mohr, A. Montanari, T. Mori, K. Nagai, I. Nakamura, H. A. Neal, B. Nellen, R. Nisius, S. W. O'Neale, F. G. Oakham, F. Odorici, H. O. Ogren, M. J. Oreglia, S. Orito, J. Pálinkás, G. Pásztor, J. R. Pater, G. N. Patrick, J. Patt, R. Perez-Ochoa, S. Petzold, P. Pfeifenschneider, J. E. Pilcher, J. Pinfold, D. E. Plane, P. Poffenberger, J. Polok, M. Przybycień, C. Rembser, H. Rick, S. Robertson, S. A. Robins, N. Rodning, J. M. Roney, K. Roscoe, A. M. Rossi, Y. Rozen, K. Runge, O. Runolfsson, D. R. Rust, K. Sachs, T. Saeki, O. Sahr, W. M. Sang, E. K.G. Sarkisyan, C. Sbarra, A. D. Schaile, O. Schaile, F. Scharf, P. Scharff-Hansen, J. Schieck, B. Schmitt, S. Schmitt, A. Schöning, M. Schröder, M. Schumacher, C. Schwick, W. G. Scott, R. Seuster, T. G. Shears, B. C. Shen, C. H. Shepherd-Themistocleous, P. Sherwood, G. P. Siroli, A. Sittler, A. Skuja, A. M. Smith, G. A. Snow, R. Sobie, S. Söldner-Rembold, M. Sproston, A. Stahl, K. Stephens, J. Steuerer, K. Stoll, D. Strom, R. Ströhmer, B. Surrow, S. D. Talbot, S. Tanaka, P. Taras, S. Tarem, R. Teuscher, M. Thiergen, M. A. Thomson, E. von Törne, E. Torrence, S. Towers, I. Trigger, Z. Trócsányi, E. Tsur, A. S. Turcot, M. F. Turner-Watson, R. van Kooten, P. Vannerem, M. Verzocchi, H. Voss, F. Wäckerle, A. Wagner, C. P. Ward, D. R. Ward, P. M. Watkins, A. T. Watson, N. K. Watson, P. S. Wells, N. Wermes, J. S. White, G. W. Wilson, J. A. Wilson, T. R. Wyatt, S. Yamashita, G. Yekutieli, V. Zacek, D. Zer-Zion

*Corresponding author for this work

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40 Scopus citations

Abstract

In the Standard Model, b quarks produced in e+e- annihilation at the Z0 peak have a large average longitudinal polarization of -0.94. Some fraction of this polarization is expected to be transferred to b-flavored baryons during hadronization. The average longitudinal polarization of weakly decaying b baryons, 〈PΛbL〉, is measured in approximately 4.3 million hadronic Z0 decays collected with the OPAL detector between 1990 and 1995 at LEP. Those b baryons that decay semileptonically and produce a Λ baryon are identified through the correlation of the baryon number of the Λ and the electric charge of the lepton. In this semileptonic decay, the ratio of the neutrino energy to the lepton energy is a sensitive polarization observable. The neutrino energy is estimated using missing energy measurements. From a fit to the distribution of this ratio, the value 〈PΛbL〉 = -0.56+0.20-0.13 ± 0.09 is obtained, where the first error is statistical and the second systematic.

Original languageEnglish
Pages (from-to)539-554
Number of pages16
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume444
Issue number3-4
DOIs
StatePublished - 24 Dec 1998

Funding

FundersFunder number
German Israeli Bi-national Science Foundation
Hungarian Foundation for Scientific ResearchOTKA T-016660, OTKA F-023259, T023793
Minerva Gesellschaft
National Science Foundation
U.S. Department of Energy
Research Corporation for Science Advancement
Natural Sciences and Engineering Research Council of Canada
National Research Council Canada
Ministry of Education, Culture, Sports, Science and Technology
Bundesministerium für Bildung und Forschung
Israel Academy of Sciences and Humanities
Israel Science Foundation

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