Phys. Rev. Lett.
93,
051801
(2004)
[5 pages]
Search for Electron Neutrino Appearance in a 250 km Long-Baseline Experiment
M. H. Ahn et al. K2K Collaboration
Show All Authors/Affiliations
Hide All Authors/Affiliations
M. H. Ahn1, S. Aoki2, Y. Ashie3, H. Bhang1, S. Boyd4,*, D. Casper5, J. H. Choi6, S. Fukuda3, Y. Fukuda7, R. Gran4, T. Hara2, M. Hasegawa8, T. Hasegawa9, K. Hayashi8, Y. Hayato10, J. Hill11,*, A. K. Ichikawa10, A. Ikeda12, T. Inagaki8,*, T. Ishida10, T. Ishii10, M. Ishitsuka3, Y. Itow3, T. Iwashita10, H. I. Jang6,*, J. S. Jang6, E. J. Jeon1, K. K. Joo1, C. K. Jung11, T. Kajita3, J. Kameda10, K. Kaneyuki3, I. Kato8, E. Kearns13, A. Kibayashi14, D. Kielczewska15,16, B. J. Kim1, C. O. Kim17, J. Y. Kim6, S. B. Kim1, K. Kobayashi11, T. Kobayashi10, Y. Koshio3, W. R. Kropp5, J. G. Learned14, S. H. Lim6, I. T. Lim6, H. Maesaka8, T. Maruyama10,*, S. Matsuno14, C. Mauger11,*, C. Mcgrew11, A. Minamino3, S. Mine5, M. Miura3, K. Miyano18, T. Morita8, S. Moriyama3, M. Nakahata3, K. Nakamura10, I. Nakano12, F. Nakata2, T. Nakaya8, S. Nakayama3, T. Namba3, R. Nambu3, K. Nishikawa8, S. Nishiyama2, S. Noda2, Y. Obayashi3, A. Okada3, Y. Oyama10, M. Y. Pac19, H. Park10,*, C. Saji3, M. Sakuda10, A. Sarrat11, T. Sasaki8, N. Sasao8, K. Scholberg20, M. Sekiguchi2, E. Sharkey11, M. Shiozawa3, K. K. Shiraishi4, M. Smy5, H. W. Sobel5, J. L. Stone13, Y. Suga2, L. R. Sulak13, A. Suzuki2, Y. Suzuki3, Y. Takeuchi3, N. Tamura18, M. Tanaka10, Y. Totsuka10, S. Ueda8, M. R. Vagins5, C. W. Walter13, W. Wang13, R. J. Wilkes4, S. Yamada3,*, S. Yamamoto8, C. Yanagisawa11, H. Yokoyama21, J. Yoo1, M. Yoshida22, and J. Zalipska16 (K2K Collaboration)
1Department of Physics, Seoul National University, Seoul 151-742, Korea
2Kobe University, Kobe, Hyogo 657-8501, Japan
3Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan
4Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
5Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, USA
6Department of Physics, Chonnam National University, Kwangju 500-757, Korea
7Department of Physics, Miyagi University of Education, Sendai 980-0845, Japan
8Department of Physics, Kyoto University, Kyoto 606-8502, Japan
9Research Center for Neutrino Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
10High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
11Department of Physics and Astronomy, State University of New York, Stony Brook, New York 11794-3800, USA
12Department of Physics, Okayama University, Okayama, Okayama 700-8530, Japan
13Department of Physics, Boston University, Boston, Massachusetts 02215, USA
14Department of Physics and Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA
15Institute of Experimental Physics, Warsaw University, 00-681 Warsaw, Poland
16A. Soltan Institute for Nuclear Studies, 00-681 Warsaw, Poland
17Department of Physics, Korea University, Seoul 136-701, Korea
18Department of Physics, Niigata University, Niigata, Niigata 950-2181, Japan
19Department of Physics, Dongshin University, Naju 520-714, Korea
20Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
21Department of Physics, Tokyo University of Science, Noda, Chiba 278-0022, Japan
22Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
Received 10 February 2004; published 27 July 2004
We present a search for electron neutrino appearance from accelerator-produced muon neutrinos in the K2K long-baseline neutrino experiment. One candidate event is found in the data corresponding to an exposure of 4.8×1019 protons on target. The expected background in the absence of neutrino oscillations is estimated to be 2.4±0.6 events and is dominated by misidentification of events from neutral current π0 production. We exclude the νμ to νe oscillations at 90% C.L. for the effective mixing angle in the 2-flavor approximation of sin22θμe(≃1/2sin22θ13)>0.15 at Δmμe2=2.8×10-3 eV2, the best-fit value of the νμ disappearance analysis in K2K. The most stringent limit of sin22θμe<0.09 is obtained at Δmμe2=6×10-3 eV2.
© 2004 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.93.051801
DOI:
10.1103/PhysRevLett.93.051801
PACS:
14.60.Pq, 13.15.+g, 23.40.Bw, 95.55.Vj
*For current affiliations see http://neutrino.kek.jp/present-addresses0401.ps
|
|
