Search for electron neutrino appearance in a 250 km long-baseline experiment.
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 x 10(19) 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 pi(0) production. We exclude the nu(micro) to nu(e) oscillations at 90% C.L. for the effective mixing angle in the 2-flavor approximation of sin((2)2theta(microe)( approximately 1/2sin((2)2theta(13))>0.15 at Deltam(2)(microe)=2.8 x 10(-3) eV(2), the best-fit value of the nu(micro) disappearance analysis in K2K. The most stringent limit of sin((2)2theta(microe)<0.09 is obtained at Deltam(2)(microe)=6 x 10(-3) eV(2).
Department of Physics, Seoul National University, Seoul 151-742, Korea.
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MH
Ahn
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Aoki
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Ashie
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H
Bhang
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Boyd
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Casper
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JH
Choi
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Fukuda
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Fukuda
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Gran
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Hara
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Hasegawa
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Hasegawa
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Hayashi
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Hayato
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Hill
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Ichikawa
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Ikeda
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Inagaki
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Ishida
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Ishii
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Ishitsuka
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Itow
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Iwashita
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Jang
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Jang
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Jeon
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KK
Joo
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CK
Jung
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Kajita
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Kameda
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Kaneyuki
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Kato
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Kearns
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Kibayashi
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Kielczewska
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BJ
Kim
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CO
Kim
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JY
Kim
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Kim
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Kobayashi
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Kobayashi
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Koshio
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Kropp
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Learned
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Lim
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Lim
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Maesaka
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Maruyama
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Matsuno
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Mauger
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C
Mcgrew
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Minamino
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Mine
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Miura
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Miyano
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Morita
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Moriyama
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Nakahata
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Nakamura
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Nakano
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F
Nakata
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T
Nakaya
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Nakayama
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T
Namba
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R
Nambu
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K
Nishikawa
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Nishiyama
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Noda
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Obayashi
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Okada
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Oyama
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MY
Pac
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Park
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C
Saji
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M
Sakuda
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A
Sarrat
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Sasaki
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N
Sasao
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Scholberg
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M
Sekiguchi
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Sharkey
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Shiozawa
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KK
Shiraishi
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M
Smy
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Sobel
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Stone
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Suga
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Sulak
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Suzuki
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Suzuki
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Takeuchi
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N
Tamura
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M
Tanaka
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Totsuka
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Ueda
M R
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Vagins
C W
CW
Walter
W
W
Wang
R J
RJ
Wilkes
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S
Yamada
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Yamamoto
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Yanagisawa
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Yokoyama
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Yoo
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Yoshida
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Zalipska