Precision Measurement of Neutrino Oscillation Parameters with KamLAND
S. AbeResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanT. EbiharaUniversity of California at BerkeleyS. EnomotoUniversity of California at BerkeleyK. FurunoResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanY. GandoResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanK. IchimuraResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanH. IkedaUniversity of California at BerkeleyK. InoueResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanY. KibeResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanY. KishimotoResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanM. KogaUniversity of California at BerkeleyA. KozlovResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanY. MinekawaResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanT. MitsuiUniversity of California at BerkeleyK. NakajimaResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanK. NakajimaResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanK. NakamuraResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanMasahiro NakamuraUniversity of California at BerkeleyK. OwadaResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanI. ShimizuUniversity of California at BerkeleyY. ShimizuResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanJ. ShiraiResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanL.F.F. StokesResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanA. SuzukiResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanY. TakemotoResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanK. TamaeResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanA. TerashimaResearch Center for Neutrino Science, Tohoku University, Sendai 980-8578, JapanH. WatanabeUniversity of California at BerkeleyE. YonezawaUniversity of California at BerkeleyS. YoshidaUniversity of California at BerkeleyJ. BusenitzDepartment of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, USAT. ClassenUniversity of California at BerkeleyC. GrantUniversity of California at BerkeleyG. KeeferDepartment of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, USAD. S. LeonardDepartment of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, USAD. McKeeUniversity of California at BerkeleyA. PiepkeDepartment of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, USAM. P. DecowskiPhysics Department, University of California, Berkeley andJ. A. DetwilerLawrence Berkeley National Laboratory, Berkeley, California 94720, USAS. J. FreedmanPhysics Department, University of California, Berkeley andB. K. FujikawaPhysics Department, University of California, Berkeley andF. GrayLawrence Berkeley National Laboratory, Berkeley, California 94720, USAE. GuardincerriUniversity of California at BerkeleyL. HsuUniversity of California at BerkeleyR. W. KadelLawrence Berkeley National Laboratory, Berkeley, California 94720, USAC. LendvaiUniversity of California at BerkeleyX.-G. LuPhysics Department, University of California, Berkeley andHitoshi MurayamaUniversity of California at BerkeleyT. O’DonnellUniversity of California at BerkeleyH. SteinerLawrence Berkeley National Laboratory, Berkeley, California 94720, USAL. A. WinslowUniversity of California at BerkeleyD. A. DwyerUniversity of California at BerkeleyC. JillingsUniversity of California at BerkeleyC. MaugerUniversity of California at BerkeleyR. D. McKeownW. K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USAP. VogelW. K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USAC. ZhangUniversity of California at BerkeleyB. E. BergerDepartment of Physics, Colorado State University, Fort Collins, Colorado 80523, USAC. LanePhysics Department, Drexel University, Philadelphia, Pennsylvania 19104, USAJ. MaricicPhysics Department, Drexel University, Philadelphia, Pennsylvania 19104, USAA. MeregagliaUniversity of California at BerkeleyM. BatygovUniversity of California at BerkeleyJ. G. LearnedDepartment of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USAS. MatsunoUniversity of California at BerkeleyS. PakvasaUniversity of California at BerkeleyJ. FosterDepartment of Physics, Kansas State University, Manhattan, Kansas 66506, USAG. A. Horton-SmithDepartment of Physics, Kansas State University, Manhattan, Kansas 66506, USAA. TangDepartment of Physics, Kansas State University, Manhattan, Kansas 66506, USAS. DazeleyUniversity of California at BerkeleyK. E. DownumPhysics Department, Stanford University, Stanford, California 94305, USAG. GrattaCenter of Quantum Universe, Okayama Uni-versity, Okayama 700-8530, JapanK. TolichCenter of Quantum Universe, Okayama Uni-versity, Okayama 700-8530, JapanW. BuggDepartment of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USAY. EfremenkoCenter of Quantum Universe, Okayama Uni-versity, Okayama 700-8530, JapanY. KamyshkovLLNL, Livermore, CA 94550, USAO. PerevozchikovUniversity of California at BerkeleyH. J. KarwowskiTriangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA andD. M. MarkoffRegis University, Denver, CO 80221, USAW. TornowRegis University, Denver, CO 80221, USAK. M. HeegerDepartment of Physics, University of Wisconsin, Madison, Wisconsin 53706, USAF. PiquemalCEN Bordeaux-Gradignan, IN2P3-CNRS and University Bordeaux I, F-33175 Gradignan Cedex, FranceJ. S. RicolCenter of Quantum Universe, Okayama Uni-versity, Okayama 700-8530, Japan
2008en
ABI
Annotatsiya
The KamLAND experiment has determined a precise value for the neutrino oscillation parameter $\ensuremath{\Delta}{m}_{21}^{2}$ and stringent constraints on ${\ensuremath{\theta}}_{12}$. The exposure to nuclear reactor antineutrinos is increased almost fourfold over previous results to $2.44\ifmmode\times\else\texttimes\fi{}{10}^{32}\text{ }\text{ }\mathrm{proton}\text{ }\mathrm{yr}$ due to longer livetime and an enlarged fiducial volume. An undistorted reactor ${\overline{\ensuremath{\nu}}}_{e}$ energy spectrum is now rejected at $>5\ensuremath{\sigma}$. Analysis of the reactor spectrum above the inverse beta decay energy threshold, and including geoneutrinos, gives a best fit at $\ensuremath{\Delta}{m}_{21}^{2}={7.58}_{\ensuremath{-}0.13}^{+0.14}(\mathrm{stat}{)}_{\ensuremath{-}0.15}^{+0.15}(\mathrm{syst})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{eV}}^{2}$ and ${tan}^{2}{\ensuremath{\theta}}_{12}={0.56}_{\ensuremath{-}0.07}^{+0.10}(\mathrm{stat}{)}_{\ensuremath{-}0.06}^{+0.10}(\mathrm{syst})$. Local $\ensuremath{\Delta}{\ensuremath{\chi}}^{2}$ minima at higher and lower $\ensuremath{\Delta}{m}_{21}^{2}$ are disfavored at $>4\ensuremath{\sigma}$. Combining with solar neutrino data, we obtain $\ensuremath{\Delta}{m}_{21}^{2}={7.59}_{\ensuremath{-}0.21}^{+0.21}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{eV}}^{2}$ and ${tan}^{2}{\ensuremath{\theta}}_{12}={0.47}_{\ensuremath{-}0.05}^{+0.06}$.
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