2006/06/30 by Myunggeun Ahn, K2K Collaboration, M. H. Ahn +99 · 9 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Neutrino #Neutrino Physics Research #Neutrino oscillation #Nuclear physics #Particle physics theoretical and experimental studies #Physics #hep-ex
paper · pdf · doi:10.1103/physrevd.74.072003
published as Phys.Rev.D74:072003,2006 · 40 pages, 48 figures
openalex publication_date 2006/10/12 · arxiv created 2006/12/25 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present measurements of \ensuremathν_\ensuremathμ disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One-hundred and twelve beam-originated neutrino events are observed in the fiducial volume of Super-Kamiokande with an expectation of 158.1_\ensuremath-8.6+9.2 events without oscillation. A distortion of the energy spectrum is also seen in 58 single-ring muonlike events with reconstructed energies. The probability that the observations are explained by the expectation for no neutrino oscillation is 0.0015% (4.3\ensuremathσ). In a two-flavor oscillation scenario, the allowed \ensuremathΔm2 region at sin22\ensuremathθ=1 is between 1.9 and 3.5\ifmmode×\else\texttimes\fi10^\ensuremath-3 eV2 at the 90% C.L. with a best-fit value of 2.8\ifmmode×\else\texttimes\fi10^\ensuremath-3 eV2.