2004/02/29 by Myunggeun Ahn, K2K Collaboration, M. H. Ahn +98 · 2 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Neutrino Physics Research #Particle physics theoretical and experimental studies #hep-ex
paper · pdf · doi:10.1103/physrevlett.93.051801
published as Phys.Rev.Lett.93:051801,2004 · 5 pages with 2 figures embeded in two column revtex4 style. Accepted to be published in Phys. Rev. Lett
arxiv created 2004/06/14 · openalex publication_date 2004/07/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
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\ifmmode×\else\texttimes\fi1019 protons on target. The expected background in the absence of neutrino oscillations is estimated to be 2.4\ifmmode±\else\textpm\fi0.6 events and is dominated by misidentification of events from neutral current \ensuremathπ0 production. We exclude the \ensuremathν_\ensuremathμ to \ensuremathνe oscillations at 90% C.L. for the effective mixing angle in the 2-flavor approximation of sin22\ensuremathθ_\ensuremathμe(\ensuremath≃(1)/(2)sin22\ensuremathθ13)>0.15 at \ensuremathΔm_\ensuremathμe2=2.8\ifmmode×\else\texttimes\fi10^\ensuremath-3 eV2, the best-fit value of the \ensuremathν_\ensuremathμ disappearance analysis in K2K. The most stringent limit of sin22\ensuremathθ_\ensuremathμe<0.09 is obtained at \ensuremathΔm_\ensuremathμe2=6\ifmmode×\else\texttimes\fi10^\ensuremath-3 eV2.