Phys. Rev. Lett.
93,
031801
(2004)
[4 pages]
Improved Measurement of the K+→π+νν̅ Branching Ratio
V. V. Anisimovsky et al. E949 Collaboration
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V. V. Anisimovsky1, A. V. Artamonov2, B. Bassalleck3, B. Bhuyan4,*, E. W. Blackmore5, D. A. Bryman6, S. Chen5, I-H. Chiang4, I.-A. Christidi7, P. S. Cooper8, M. V. Diwan4, J. S. Frank4, T. Fujiwara9, J. Hu5, A. P. Ivashkin1, D. E. Jaffe4, S. Kabe10, S. H. Kettell4, M. M. Khabibullin1, A. N. Khotjantsev1, P. Kitching11, M. Kobayashi10, T. K. Komatsubara10, A. Konaka5, A. P. Kozhevnikov2, Yu. G. Kudenko1, A. Kushnirenko8,†, L. G. Landsberg2, B. Lewis3, K. K. Li4, L. S. Littenberg4, J. A. Macdonald5,‡, J. Mildenberger5, O. V. Mineev1, M. Miyajima12, K. Mizouchi9, V. A. Mukhin2, N. Muramatsu13,§, T. Nakano13, M. Nomachi14, T. Nomura9, T. Numao5, V. F. Obraztsov2, K. Omata10, D. I. Patalakha2, S. V. Petrenko2, R. Poutissou5, E. J. Ramberg8, G. Redlinger4, T. Sato10, T. Sekiguchi10, T. Shinkawa15, R. C. Strand4, S. Sugimoto10, Y. Tamagawa12, R. Tschirhart8, T. Tsunemi10, D. V. Vavilov2, B. Viren4, N. V. Yershov1, Y. Yoshimura10, and T. Yoshioka10 (E949 Collaboration)
1Institute for Nuclear Research RAS, 60 October Revolution Prospect 7a, 117312 Moscow, Russia
2Institute for High Energy Physics, Protvino, Moscow Region, 142 280, Russia
3Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, USA
4Brookhaven National Laboratory, Upton, New York 11973, USA
5TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 Canada
6Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, V6T 1Z1 Canada
7Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
8Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
9Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
10High Energy Accelerator Research Organization (KEK), Oho, Tsukuba, Ibaraki 305-0801, Japan
11Centre for Subatomic Research, University of Alberta, Edmonton, T6G 2N5 Canada
12Department of Applied Physics, Fukui University, 3-9-1 Bunkyo, Fukui, Fukui 910-8507, Japan
13Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
14Laboratory of Nuclear Studies, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
15Department of Applied Physics, National Defense Academy, Yokosuka, Kanagawa 239-8686, Japan
Received 19 March 2004; published 12 July 2004
An additional event near the upper kinematic limit for K+→π+νν̅ has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+→π+νν̅ )=(1.47-0.89+1.30)×10-10 based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.
© 2004 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.93.031801
DOI:
10.1103/PhysRevLett.93.031801
PACS:
13.20.Eb, 12.15.Hh, 14.80.Mz
*Present address: Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, V8W 3P6 Canada. Also at the Department of Physics, University of Delhi, Delhi 1100007, India. †Present address: Institute for High Energy Physics, Protvino, Moscow Region, 142 280, Russia. ‡Deceased. §Present address: Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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