APS » PROLA » Phys. Rev. Lett. » Volume 93 » Issue 5

Phys. Rev. Lett. 93, 051801 (2004) [5 pages]

Search for Electron Neutrino Appearance in a 250 km Long-Baseline Experiment
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M. H. Ahn et al. K2K Collaboration
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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 sin⁡22θμe(≃1 / 2sin⁡22θ13)>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 sin⁡22θμe<0.09 is obtained at Δmμe2=6×10-3   eV2.


©2004 The American Physical Society

URL: http://link.aps.org/abstract/PRL/v93/e051801
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

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