Search for Lorentz and CPT violation using sidereal time dependence of neutrino flavor transitions over a short baseline

Search for Lorentz and CPT violation using sidereal time dependence of neutrino flavor transitions over a short baseline

K. Abe University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    J. Amey Imperial College London, Department of Physics, London, United Kingdom    C. Andreopoulos STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom University of Liverpool, Department of Physics, Liverpool, United Kingdom    M. Antonova Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    S. Aoki Kobe University, Kobe, Japan    A. Ariga University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), Bern, Switzerland    S. Assylbekov Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    D. Autiero Université de Lyon, Université Claude Bernard Lyon 1, IPN Lyon (IN2P3), Villeurbanne, France    S. Ban Kyoto University, Department of Physics, Kyoto, Japan    F.C.T. Barbato INFN Sezione di Napoli and Università di Napoli, Dipartimento di Fisica, Napoli, Italy    M. Barbi University of Regina, Department of Physics, Regina, Saskatchewan, Canada    G.J. Barker University of Warwick, Department of Physics, Coventry, United Kingdom    G. Barr Oxford University, Department of Physics, Oxford, United Kingdom    C. Barry University of Liverpool, Department of Physics, Liverpool, United Kingdom    P. Bartet-Friburg UPMC, Université Paris Diderot, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Paris, France    M. Batkiewicz H. Niewodniczanski Institute of Nuclear Physics PAN, Cracow, Poland    V. Berardi INFN Sezione di Bari and Università e Politecnico di Bari, Dipartimento Interuniversitario di Fisica, Bari, Italy    S. Berkman University of British Columbia, Department of Physics and Astronomy, Vancouver, British Columbia, Canada TRIUMF, Vancouver, British Columbia, Canada    S. Bhadra York University, Department of Physics and Astronomy, Toronto, Ontario, Canada    S. Bienstock UPMC, Université Paris Diderot, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Paris, France    A. Blondel University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    S. Bolognesi IRFU, CEA Saclay, Gif-sur-Yvette, France    S. Bordoni Institut de Fisica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra (Barcelona) Spain    S.B. Boyd University of Warwick, Department of Physics, Coventry, United Kingdom    D. Brailsford Lancaster University, Physics Department, Lancaster, United Kingdom    A. Bravar University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    C. Bronner Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    M. Buizza Avanzini Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France    R.G. Calland Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    T. Campbell Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    S. Cao High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    S.L. Cartwright University of Sheffield, Department of Physics and Astronomy, Sheffield, United Kingdom    R. Castillo Institut de Fisica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra (Barcelona) Spain    M.G. Catanesi INFN Sezione di Bari and Università e Politecnico di Bari, Dipartimento Interuniversitario di Fisica, Bari, Italy    A. Cervera IFIC (CSIC & University of Valencia), Valencia, Spain    A. Chappell University of Warwick, Department of Physics, Coventry, United Kingdom    C. Checchia INFN Sezione di Padova and Università di Padova, Dipartimento di Fisica, Padova, Italy    D. Cherdack Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    N. Chikuma University of Tokyo, Department of Physics, Tokyo, Japan    G. Christodoulou University of Liverpool, Department of Physics, Liverpool, United Kingdom    A. Clifton Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    J. Coleman University of Liverpool, Department of Physics, Liverpool, United Kingdom    G. Collazuol INFN Sezione di Padova and Università di Padova, Dipartimento di Fisica, Padova, Italy    D. Coplowe Oxford University, Department of Physics, Oxford, United Kingdom    L. Cremonesi Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    A. Cudd Michigan State University, Department of Physics and Astronomy, East Lansing, Michigan, U.S.A.    A. Dabrowska H. Niewodniczanski Institute of Nuclear Physics PAN, Cracow, Poland    G. De Rosa INFN Sezione di Napoli and Università di Napoli, Dipartimento di Fisica, Napoli, Italy    T. Dealtry Lancaster University, Physics Department, Lancaster, United Kingdom    P.F. Denner University of Warwick, Department of Physics, Coventry, United Kingdom    S.R. Dennis University of Liverpool, Department of Physics, Liverpool, United Kingdom    C. Densham STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom    D. Dewhurst Oxford University, Department of Physics, Oxford, United Kingdom    F. Di Lodovico Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    S. Di Luise ETH Zurich, Institute for Particle Physics, Zurich, Switzerland    S. Dolan Oxford University, Department of Physics, Oxford, United Kingdom    O. Drapier Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France    K.E. Duffy Oxford University, Department of Physics, Oxford, United Kingdom    J. Dumarchez UPMC, Université Paris Diderot, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Paris, France    M. Dunkman Michigan State University, Department of Physics and Astronomy, East Lansing, Michigan, U.S.A.    M. Dziewiecki Warsaw University of Technology, Institute of Radioelectronics, Warsaw, Poland    S. Emery-Schrenk IRFU, CEA Saclay, Gif-sur-Yvette, France    A. Ereditato University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), Bern, Switzerland    T. Feusels University of British Columbia, Department of Physics and Astronomy, Vancouver, British Columbia, Canada TRIUMF, Vancouver, British Columbia, Canada    A.J. Finch Lancaster University, Physics Department, Lancaster, United Kingdom    G.A. Fiorentini York University, Department of Physics and Astronomy, Toronto, Ontario, Canada    M. Friend High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    Y. Fujii High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    D. Fukuda Okayama University, Department of Physics, Okayama, Japan    Y. Fukuda Miyagi University of Education, Department of Physics, Sendai, Japan    A.P. Furmanski University of Warwick, Department of Physics, Coventry, United Kingdom    V. Galymov Université de Lyon, Université Claude Bernard Lyon 1, IPN Lyon (IN2P3), Villeurbanne, France    A. Garcia Institut de Fisica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra (Barcelona) Spain    S.G. Giffin University of Regina, Department of Physics, Regina, Saskatchewan, Canada    C. Giganti UPMC, Université Paris Diderot, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Paris, France    F. Gizzarelli IRFU, CEA Saclay, Gif-sur-Yvette, France    T. Golan Wroclaw University, Faculty of Physics and Astronomy, Wroclaw, Poland    M. Gonin Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France    N. Grant University of Warwick, Department of Physics, Coventry, United Kingdom    D.R. Hadley University of Warwick, Department of Physics, Coventry, United Kingdom    L. Haegel University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    J.T. Haigh University of Warwick, Department of Physics, Coventry, United Kingdom    P. Hamilton Imperial College London, Department of Physics, London, United Kingdom    D. Hansen University of Pittsburgh, Department of Physics and Astronomy, Pittsburgh, Pennsylvania, U.S.A.    J. Harada Osaka City University, Department of Physics, Osaka, Japan    T. Hara Kobe University, Kobe, Japan    M. Hartz Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan TRIUMF, Vancouver, British Columbia, Canada    T. Hasegawa High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    N.C. Hastings University of Regina, Department of Physics, Regina, Saskatchewan, Canada    T. Hayashino Kyoto University, Department of Physics, Kyoto, Japan    Y. Hayato University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    R.L. Helmer TRIUMF, Vancouver, British Columbia, Canada    M. Hierholzer University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), Bern, Switzerland    A. Hillairet University of Victoria, Department of Physics and Astronomy, Victoria, British Columbia, Canada    A. Himmel Duke University, Department of Physics, Durham, North Carolina, U.S.A.    T. Hiraki Kyoto University, Department of Physics, Kyoto, Japan    A. Hiramoto Kyoto University, Department of Physics, Kyoto, Japan    S. Hirota Kyoto University, Department of Physics, Kyoto, Japan    M. Hogan Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    J. Holeczek University of Silesia, Institute of Physics, Katowice, Poland    F. Hosomi University of Tokyo, Department of Physics, Tokyo, Japan    K. Huang Kyoto University, Department of Physics, Kyoto, Japan    A.K. Ichikawa Kyoto University, Department of Physics, Kyoto, Japan    K. Ieki Kyoto University, Department of Physics, Kyoto, Japan    M. Ikeda University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    J. Imber Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France    J. Insler Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, U.S.A.    R.A. Intonti INFN Sezione di Bari and Università e Politecnico di Bari, Dipartimento Interuniversitario di Fisica, Bari, Italy    T.J. Irvine University of Tokyo, Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, Kashiwa, Japan    T. Ishida High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    T. Ishii High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    E. Iwai High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    K. Iwamoto University of Rochester, Department of Physics and Astronomy, Rochester, New York, U.S.A.    A. Izmaylov IFIC (CSIC & University of Valencia), Valencia, Spain Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    A. Jacob Oxford University, Department of Physics, Oxford, United Kingdom    B. Jamieson University of Winnipeg, Department of Physics, Winnipeg, Manitoba, Canada    M. Jiang Kyoto University, Department of Physics, Kyoto, Japan    S. Johnson University of Colorado at Boulder, Department of Physics, Boulder, Colorado, U.S.A.    J.H. Jo State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    P. Jonsson Imperial College London, Department of Physics, London, United Kingdom    C.K. Jung State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    M. Kabirnezhad National Centre for Nuclear Research, Warsaw, Poland    A.C. Kaboth Royal Holloway University of London, Department of Physics, Egham, Surrey, United Kingdom STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom    T. Kajita University of Tokyo, Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, Kashiwa, Japan    H. Kakuno Tokyo Metropolitan University, Department of Physics, Tokyo, Japan    J. Kameda University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    D. Karlen University of Victoria, Department of Physics and Astronomy, Victoria, British Columbia, Canada TRIUMF, Vancouver, British Columbia, Canada    I. Karpikov Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    T. Katori Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    E. Kearns Boston University, Department of Physics, Boston, Massachusetts, U.S.A. Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    M. Khabibullin Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    A. Khotjantsev Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    D. Kielczewska University of Warsaw, Faculty of Physics, Warsaw, Poland    T. Kikawa Kyoto University, Department of Physics, Kyoto, Japan    H. Kim Osaka City University, Department of Physics, Osaka, Japan    J. Kim University of British Columbia, Department of Physics and Astronomy, Vancouver, British Columbia, Canada TRIUMF, Vancouver, British Columbia, Canada    S. King Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    J. Kisiel University of Silesia, Institute of Physics, Katowice, Poland    A. Knight University of Warwick, Department of Physics, Coventry, United Kingdom    A. Knox Lancaster University, Physics Department, Lancaster, United Kingdom    T. Kobayashi High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    L. Koch RWTH Aachen University, III. Physikalisches Institut, Aachen, Germany    T. Koga University of Tokyo, Department of Physics, Tokyo, Japan    A. Konaka TRIUMF, Vancouver, British Columbia, Canada    K. Kondo Kyoto University, Department of Physics, Kyoto, Japan    A. Kopylov Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    L.L. Kormos Lancaster University, Physics Department, Lancaster, United Kingdom    A. Korzenev University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    Y. Koshio Okayama University, Department of Physics, Okayama, Japan    K. Kowalik National Centre for Nuclear Research, Warsaw, Poland    W. Kropp University of California, Irvine, Department of Physics and Astronomy, Irvine, California, U.S.A.    Y. Kudenko Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    R. Kurjata Warsaw University of Technology, Institute of Radioelectronics, Warsaw, Poland    T. Kutter Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, U.S.A.    J. Lagoda National Centre for Nuclear Research, Warsaw, Poland    I. Lamont Lancaster University, Physics Department, Lancaster, United Kingdom    M. Lamoureux IRFU, CEA Saclay, Gif-sur-Yvette, France    E. Larkin University of Warwick, Department of Physics, Coventry, United Kingdom    P. Lasorak Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    M. Laveder INFN Sezione di Padova and Università di Padova, Dipartimento di Fisica, Padova, Italy    M. Lawe Lancaster University, Physics Department, Lancaster, United Kingdom    M. Lazos University of Liverpool, Department of Physics, Liverpool, United Kingdom    M. Licciardi Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France    T. Lindner TRIUMF, Vancouver, British Columbia, Canada    Z.J. Liptak University of Colorado at Boulder, Department of Physics, Boulder, Colorado, U.S.A.    R.P. Litchfield Imperial College London, Department of Physics, London, United Kingdom    X. Li State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    A. Longhin INFN Sezione di Padova and Università di Padova, Dipartimento di Fisica, Padova, Italy    J.P. Lopez University of Colorado at Boulder, Department of Physics, Boulder, Colorado, U.S.A.    T. Lou University of Tokyo, Department of Physics, Tokyo, Japan    L. Ludovici INFN Sezione di Roma and Università di Roma “La Sapienza”, Roma, Italy    X. Lu Oxford University, Department of Physics, Oxford, United Kingdom    L. Magaletti INFN Sezione di Bari and Università e Politecnico di Bari, Dipartimento Interuniversitario di Fisica, Bari, Italy    K. Mahn Michigan State University, Department of Physics and Astronomy, East Lansing, Michigan, U.S.A.    M. Malek University of Sheffield, Department of Physics and Astronomy, Sheffield, United Kingdom    S. Manly University of Rochester, Department of Physics and Astronomy, Rochester, New York, U.S.A.    L. Maret University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    A.D. Marino University of Colorado at Boulder, Department of Physics, Boulder, Colorado, U.S.A.    J. Marteau Université de Lyon, Université Claude Bernard Lyon 1, IPN Lyon (IN2P3), Villeurbanne, France    J.F. Martin University of Toronto, Department of Physics, Toronto, Ontario, Canada    P. Martins Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    S. Martynenko State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    T. Maruyama High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    V. Matveev Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    K. Mavrokoridis University of Liverpool, Department of Physics, Liverpool, United Kingdom    W.Y. Ma Imperial College London, Department of Physics, London, United Kingdom    E. Mazzucato IRFU, CEA Saclay, Gif-sur-Yvette, France    M. McCarthy York University, Department of Physics and Astronomy, Toronto, Ontario, Canada    N. McCauley University of Liverpool, Department of Physics, Liverpool, United Kingdom    K.S. McFarland University of Rochester, Department of Physics and Astronomy, Rochester, New York, U.S.A.    C. McGrew State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    A. Mefodiev Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    C. Metelko University of Liverpool, Department of Physics, Liverpool, United Kingdom    M. Mezzetto INFN Sezione di Padova and Università di Padova, Dipartimento di Fisica, Padova, Italy    P. Mijakowski National Centre for Nuclear Research, Warsaw, Poland    A. Minamino Yokohama National University, Faculty of Engineering, Yokohama, Japan    O. Mineev Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    S. Mine University of California, Irvine, Department of Physics and Astronomy, Irvine, California, U.S.A.    A. Missert University of Colorado at Boulder, Department of Physics, Boulder, Colorado, U.S.A.    M. Miura University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    S. Moriyama University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    J. Morrison Michigan State University, Department of Physics and Astronomy, East Lansing, Michigan, U.S.A.    Th.A. Mueller Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France    S. Murphy ETH Zurich, Institute for Particle Physics, Zurich, Switzerland    J. Myslik University of Victoria, Department of Physics and Astronomy, Victoria, British Columbia, Canada    T. Nakadaira High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    M. Nakahata University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    K.G. Nakamura Kyoto University, Department of Physics, Kyoto, Japan    K. Nakamura Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    K.D. Nakamura Kyoto University, Department of Physics, Kyoto, Japan    Y. Nakanishi Kyoto University, Department of Physics, Kyoto, Japan    S. Nakayama University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    T. Nakaya Kyoto University, Department of Physics, Kyoto, Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    K. Nakayoshi High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    C. Nantais University of Toronto, Department of Physics, Toronto, Ontario, Canada    C. Nielsen University of British Columbia, Department of Physics and Astronomy, Vancouver, British Columbia, Canada    M. Nirkko University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), Bern, Switzerland    K. Nishikawa High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    Y. Nishimura University of Tokyo, Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, Kashiwa, Japan    P. Novella IFIC (CSIC & University of Valencia), Valencia, Spain    J. Nowak Lancaster University, Physics Department, Lancaster, United Kingdom    H.M. O’Keeffe Lancaster University, Physics Department, Lancaster, United Kingdom    R. Ohta High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    K. Okumura University of Tokyo, Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, Kashiwa, Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    T. Okusawa Osaka City University, Department of Physics, Osaka, Japan    W. Oryszczak University of Warsaw, Faculty of Physics, Warsaw, Poland    S.M. Oser University of British Columbia, Department of Physics and Astronomy, Vancouver, British Columbia, Canada TRIUMF, Vancouver, British Columbia, Canada    T. Ovsyannikova Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    R.A. Owen Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    Y. Oyama High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    V. Palladino INFN Sezione di Napoli and Università di Napoli, Dipartimento di Fisica, Napoli, Italy    J.L. Palomino State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    V. Paolone University of Pittsburgh, Department of Physics and Astronomy, Pittsburgh, Pennsylvania, U.S.A.    N.D. Patel Kyoto University, Department of Physics, Kyoto, Japan    P. Paudyal University of Liverpool, Department of Physics, Liverpool, United Kingdom    M. Pavin UPMC, Université Paris Diderot, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Paris, France    D. Payne University of Liverpool, Department of Physics, Liverpool, United Kingdom    J.D. Perkin University of Sheffield, Department of Physics and Astronomy, Sheffield, United Kingdom    Y. Petrov University of British Columbia, Department of Physics and Astronomy, Vancouver, British Columbia, Canada TRIUMF, Vancouver, British Columbia, Canada    L. Pickard University of Sheffield, Department of Physics and Astronomy, Sheffield, United Kingdom    L. Pickering Imperial College London, Department of Physics, London, United Kingdom    E.S. Pinzon Guerra York University, Department of Physics and Astronomy, Toronto, Ontario, Canada    C. Pistillo University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), Bern, Switzerland    B. Popov UPMC, Université Paris Diderot, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Paris, France    M. Posiadala-Zezula University of Warsaw, Faculty of Physics, Warsaw, Poland    J.-M. Poutissou TRIUMF, Vancouver, British Columbia, Canada    R. Poutissou TRIUMF, Vancouver, British Columbia, Canada    P. Przewlocki National Centre for Nuclear Research, Warsaw, Poland    B. Quilain Kyoto University, Department of Physics, Kyoto, Japan    T. Radermacher RWTH Aachen University, III. Physikalisches Institut, Aachen, Germany    E. Radicioni INFN Sezione di Bari and Università e Politecnico di Bari, Dipartimento Interuniversitario di Fisica, Bari, Italy    P.N. Ratoff Lancaster University, Physics Department, Lancaster, United Kingdom    M. Ravonel University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    M.A. Rayner University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    A. Redij University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), Bern, Switzerland    E. Reinherz-Aronis Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    C. Riccio INFN Sezione di Napoli and Università di Napoli, Dipartimento di Fisica, Napoli, Italy    P. Rojas Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    E. Rondio National Centre for Nuclear Research, Warsaw, Poland    B. Rossi INFN Sezione di Napoli and Università di Napoli, Dipartimento di Fisica, Napoli, Italy    S. Roth RWTH Aachen University, III. Physikalisches Institut, Aachen, Germany    A. Rubbia ETH Zurich, Institute for Particle Physics, Zurich, Switzerland    A.C. Ruggeri INFN Sezione di Napoli and Università di Napoli, Dipartimento di Fisica, Napoli, Italy    A. Rychter Warsaw University of Technology, Institute of Radioelectronics, Warsaw, Poland    R. Sacco Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    K. Sakashita High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    F. Sánchez Institut de Fisica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra (Barcelona) Spain    F. Sato High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    E. Scantamburlo University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    K. Scholberg Duke University, Department of Physics, Durham, North Carolina, U.S.A.    J. Schwehr Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    M. Scott TRIUMF, Vancouver, British Columbia, Canada    Y. Seiya Osaka City University, Department of Physics, Osaka, Japan    T. Sekiguchi High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    H. Sekiya University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    D. Sgalaberna University of Geneva, Section de Physique, DPNC, Geneva, Switzerland    R. Shah STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom Oxford University, Department of Physics, Oxford, United Kingdom    A. Shaikhiev Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    F. Shaker University of Winnipeg, Department of Physics, Winnipeg, Manitoba, Canada    D. Shaw Lancaster University, Physics Department, Lancaster, United Kingdom    M. Shiozawa University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    T. Shirahige Okayama University, Department of Physics, Okayama, Japan    S. Short Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    M. Smy University of California, Irvine, Department of Physics and Astronomy, Irvine, California, U.S.A.    J.T. Sobczyk Wroclaw University, Faculty of Physics and Astronomy, Wroclaw, Poland    H. Sobel University of California, Irvine, Department of Physics and Astronomy, Irvine, California, U.S.A. Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    M. Sorel IFIC (CSIC & University of Valencia), Valencia, Spain    L. Southwell Lancaster University, Physics Department, Lancaster, United Kingdom    P. Stamoulis IFIC (CSIC & University of Valencia), Valencia, Spain    J. Steinmann RWTH Aachen University, III. Physikalisches Institut, Aachen, Germany    T. Stewart STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom    P. Stowell University of Sheffield, Department of Physics and Astronomy, Sheffield, United Kingdom    Y. Suda University of Tokyo, Department of Physics, Tokyo, Japan    S. Suvorov Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    A. Suzuki Kobe University, Kobe, Japan    K. Suzuki Kyoto University, Department of Physics, Kyoto, Japan    S.Y. Suzuki High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    Y. Suzuki Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    R. Tacik University of Regina, Department of Physics, Regina, Saskatchewan, Canada TRIUMF, Vancouver, British Columbia, Canada    M. Tada High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    S. Takahashi Kyoto University, Department of Physics, Kyoto, Japan    A. Takeda University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    Y. Takeuchi Kobe University, Kobe, Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    R. Tamura University of Tokyo, Department of Physics, Tokyo, Japan    H.K. Tanaka University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    H.A. Tanaka University of Toronto, Department of Physics, Toronto, Ontario, Canada TRIUMF, Vancouver, British Columbia, Canada    D. Terhorst RWTH Aachen University, III. Physikalisches Institut, Aachen, Germany    R. Terri Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    T. Thakore Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, U.S.A.    L.F. Thompson University of Sheffield, Department of Physics and Astronomy, Sheffield, United Kingdom    S. Tobayama University of British Columbia, Department of Physics and Astronomy, Vancouver, British Columbia, Canada TRIUMF, Vancouver, British Columbia, Canada    W. Toki Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    T. Tomura University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan    C. Touramanis University of Liverpool, Department of Physics, Liverpool, United Kingdom    T. Tsukamoto High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    M. Tzanov Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, U.S.A.    Y. Uchida Imperial College London, Department of Physics, London, United Kingdom    A. Vacheret Imperial College London, Department of Physics, London, United Kingdom    M. Vagins Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan University of California, Irvine, Department of Physics and Astronomy, Irvine, California, U.S.A.    Z. Vallari State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    G. Vasseur IRFU, CEA Saclay, Gif-sur-Yvette, France    C. Vilela State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    T. Vladisavljevic Oxford University, Department of Physics, Oxford, United Kingdom Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan    T. Wachala H. Niewodniczanski Institute of Nuclear Physics PAN, Cracow, Poland    K. Wakamatsu Osaka City University, Department of Physics, Osaka, Japan    C.W. Walter Duke University, Department of Physics, Durham, North Carolina, U.S.A.    D. Wark STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom Oxford University, Department of Physics, Oxford, United Kingdom    W. Warzycha University of Warsaw, Faculty of Physics, Warsaw, Poland    M.O. Wascko Imperial College London, Department of Physics, London, United Kingdom    A. Weber STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom Oxford University, Department of Physics, Oxford, United Kingdom    R. Wendell Kyoto University, Department of Physics, Kyoto, Japan    R.J. Wilkes University of Washington, Department of Physics, Seattle, Washington, U.S.A.    M.J. Wilking State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    C. Wilkinson University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), Bern, Switzerland    J.R. Wilson Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom    R.J. Wilson Colorado State University, Department of Physics, Fort Collins, Colorado, U.S.A.    C. Wret Imperial College London, Department of Physics, London, United Kingdom    Y. Yamada High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    K. Yamamoto Osaka City University, Department of Physics, Osaka, Japan    M. Yamamoto Kyoto University, Department of Physics, Kyoto, Japan    C. Yanagisawa State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, New York, U.S.A.    T. Yano Kobe University, Kobe, Japan    S. Yen TRIUMF, Vancouver, British Columbia, Canada    N. Yershov Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia    M. Yokoyama University of Tokyo, Department of Physics, Tokyo, Japan    J. Yoo Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, U.S.A.    K. Yoshida Kyoto University, Department of Physics, Kyoto, Japan    T. Yuan University of Colorado at Boulder, Department of Physics, Boulder, Colorado, U.S.A.    M. Yu York University, Department of Physics and Astronomy, Toronto, Ontario, Canada    A. Zalewska H. Niewodniczanski Institute of Nuclear Physics PAN, Cracow, Poland    J. Zalipska National Centre for Nuclear Research, Warsaw, Poland    L. Zambelli High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan    K. Zaremba Warsaw University of Technology, Institute of Radioelectronics, Warsaw, Poland    M. Ziembicki Warsaw University of Technology, Institute of Radioelectronics, Warsaw, Poland    E.D. Zimmerman University of Colorado at Boulder, Department of Physics, Boulder, Colorado, U.S.A.    M. Zito IRFU, CEA Saclay, Gif-sur-Yvette, France    J. Żmuda Wroclaw University, Faculty of Physics and Astronomy, Wroclaw, Poland
Abstract

A class of extensions of the Standard Model allows Lorentz and CPT violations, which can be identified by the observation of sidereal modulations in the neutrino interaction rate. A search for such modulations was performed using the T2K on-axis near detector. Two complementary methods were used in this study, both of which resulted in no evidence of a signal. Limits on associated Lorentz and CPT violating terms from the Standard Model Extension have been derived taking into account their correlations in this model for the first time. These results imply such symmetry violations are suppressed by a factor of more than at the GeV scale.

thanks: now at CERNthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: deceasedthanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at National Research Nuclear University “MEPhI” and Moscow Institute of Physics and Technology, Moscow, Russiathanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at JINR, Dubna, Russiathanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at Institute of Particle Physics, Canadathanks: also at J-PARC, Tokai, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at J-PARC, Tokai, Japanthanks: also at BMCC/CUNY, Science Department, New York, New York, U.S.A.thanks: affiliated member at Kavli IPMU (WPI), the University of Tokyo, Japanthanks: also at J-PARC, Tokai, Japan

The T2K Collaboration

I Introduction

While Lorentz invariance is a cornerstone of the Standard Model (SM) of particle physics, violations of this symmetry are allowed in a variety of models Kostelecký and Samuel (1989); Hawking (1976); Hinchliffe et al. (2004) at or around the Planck scale, GeV. At energies relevant to modern experiments, Lorentz invariance violating (LV) processes are expected to be suppressed at least by . Experimental observations of such phenomena would provide direct access to physics at the Planck scale and precision tests have been performed to overcome this suppression (c.f. Kostelecký and Russell (2011) for a review). Neutrino oscillations can be used as a natural interferometer to probe even weak departures from this symmetry and have been studied with accelerator Auerbach et al. (2005); Aguilar-Arevalo et al. (2013); Adamson et al. (2008, 2012, 2010); Rebel et al. (2013), reactor Abe et al. (2012), and atmospheric Abbasi et al. (2010); Abe and others (Super-Kamiokande Collaboration) (2015) neutrinos.

Lorentz and charge-parity-time (CPT) symmetry violations can be described within the context of the standard model extension (SME) Colladay and Kostelecký (1998), an observer-independent effective field theory that incorporates all possible spontaneous LV operators with the SM Lagrangian. In general the SME allows two classes of effects for neutrino oscillations, sidereal violations, in which the presence of a preferred spatial direction induces oscillation effects that vary with the neutrino travel direction, and spectral anomalies Kostelecký and Mewes (2012, 2004a, 2004b). For a terrestrial fixed-baseline experiment, the rotation of the Earth induces a change in the direction of the neutrino target-detector vector relative to a fixed coordinate system such that a LV signal of the former type would manifest itself as a variation in the neutrino oscillation probability with sidereal time.

This paper reports on a search for evidence of sidereal-dependent disappearance over an average baseline of 233.6 m using the T2K experiment. After introducing Lorentz invariance violating oscillations within the SME and describing the T2K experiment, the selection of an analysis sample composed predominately of muon neutrinos inside the INGRID Abe and others (T2K Collaboration) (2011, 2012) detector is presented. Results of two complementary analyses of the data and concluding remarks follow thereafter.

Ii LV effects on neutrino oscillations at short distances

In this analysis, the LV is probed through disappearance channel. In the SME framework, the disappearance probability of a over short baselines is given by Kostelecký and Mewes (2004a):

(1)

where is the distance travelled before detection. Equation (1) is valid as long as , where is the typical distance of standard oscillations K. A. Olive et al. (2012). is the local sidereal time and is the Earth’s sidereal frequency. Under a three flavour neutrino hypothesis, oscillations of to and can occur. In general, the ten coefficients , , , , and () are functions of the neutrino energy , the neutrino beam direction at the time origin (see below), and of forty parameters within the SME which carry explicit Lorentz and CPT violation information: and (Diaz et al. (2009). The () are constant coefficients associated with CPT odd (even) vector (tensor) fields. It should be noted that the impact of and on the set of ten coefficients depend on the absolute direction of the neutrino baseline Diaz et al. (2009). In the analysis to follow, a search for a sidereal variations is performed relative to an inertial frame centered on the Sun assuming it to be stationary during the data taking period. Other than the choice of the origin of the time coordinate, this frame is the same as in Katori (2012). The time origin is chosen as 1 January 1970, 09:00:00 Coordinated Universal Time. Data will be studied using the local sidereal phase (LSP), which is defined as .

Iii Experimental setup

The T2K long-baseline neutrino experiment uses the collision of 30 GeV protons from the Japan Proton Accelerator Research Complex (J-PARC) with a graphite target, and focuses charged mesons produced in the subsequent interactions along the primary proton beam direction using a series of magnetic horns. Downstream of the production target is a 96 m long decay volume in which these mesons decay to produce a beam of primarily muon neutrinos ( along the beam axis).

This study is based on data accumulated from 2010 to 2013, divided into four run periods, and corresponds to protons on target (POT) exposure of the INGRID detector in neutrino-mode. The neutrino beam is defined by the beam colatitude in the Earth-centered frame with the same fixed axis than the Sun-centered frame. At the beamline location, a local frame is defined where the z-axis corresponds to the zenith. The beam direction in this local frame is defined by the zenith angle and at the azimuthal angle . A more detailed description of the T2K experiment can be found in Abe and others (T2K Collaboration) (2011).

The INGRID detector is located  m downstream of the graphite target and is composed of 14  cm cmcm modules assembled in a cross-shaped structure. Each module holds 11 tracking segments built from pairs of orthogonally oriented scintillator planes interleaved with nine iron planes. The scintillator planes are built from 24 plastic scintillator bars connected to multi-pixel photon counters (MPPCs). Situated on the beam center, INGRID high event rate makes it well suited to a search for a sidereal variation in the interactions.

Although the oscillation probability in Equation (1) depends on the square of the neutrino flight length, the precise distance from creation to detection for each neutrino is unknown. Indeed, the neutrino’s parent meson may decay anywhere along the decay volume as shown in Figure 1. As a result the present analysis uses the mean of this distribution,  m, as an effective distance travelled for all candidate events. Similarly, the mean neutrino energy of the flux at the INGRID detector, , is used.

Figure 1: Flight length to the INGRID detector for MC produced in the T2K decay volume. The distribution is separated based on the neutrino’s parent particle.

Iv Event Selection and Systematic Uncertainties

iv.1 The INGRID event selection

To prevent LV oscillation-induced and from washing out an LV effect on the data, it is essential to select a sample with very high purity. Since the CC interactions have a 3.5 GeV production threshold, their cross section in the T2K energy range is very small. Their impact on the analysis was evaluated to be negligible. Consequently, no attempts were made to further reject them in the signal selection.
Charged-current neutrino interactions within INGRID are identified by a reconstructed track consistent with a muon originating in the detector fiducial volume, and coincident in time with the expected arrival of neutrinos in the beam originated from a given proton bunch. In addition to a set of cuts to define a basic lepton-like sample Abe and others (T2K Collaboration) (2014), a likelihood function, hereafter referred to as muon confidence level (), is used to further separate tracks produced by muons from showers produced by electrons or hadrons. This function is based on four discriminating variables: the number of active scintillator bars transverse to the beam direction averaged over the number of active planes, i.e. planes having at least one hit belonging to the track; the primary track’s length; the dispersion of the track’s energy deposition with distance; and the number of active scintillator bars close to the primary interaction vertex. The first three variables focus on the tendency for showers to have a broader transverse development and varying rate of energy deposition, whereas muons at T2K energies are minimum ionizing and are more longitudinally penetrating. The fourth variable is based on a region defined by only the two planes upstream and downstream of the event vertex and is useful for discriminating against showers with additional particles near the event vertex and proton-induced activity. Since the total neutrino flux is constant and the neutral current (NC) cross section is the same for each neutrino flavor, the NC event rate within INGRID is expected to be constant with sidereal time. Accordingly, no additional cuts to remove NC events are used. Figure 2 shows the likelihood distribution for reconstructed data and Monte Carlo (MC) CC, CC and NC interactions.

Figure 2: Distribution of the variable for CC (blue), CC (red), and NC events (green) from the MC are overlaid with data (black). The data, CC and NC histograms are first normalized by protons on target, and then, scaled by one over the number of CC events to preserve their relative proportions. The CC histogram is area normalized to compare with the CC histogram. The pink arrow represents the lower cut value on the that defines the event selection.

A cut on has been selected to ensure that the contamination of the final sample is smaller than the statistical error on the component while maximizing the statistics. After applying all analysis cuts the CC selection efficiency is . The corresponding efficiency, , has been reduced to . There are events remaining in the final sample, which provides an average statistical error of in each of the 32 analysis bins (defined below). If an oscillation effect equivalent to three times the statistical error on the component appears as in the final sample the resulting contamination will be . Assuming no oscillation due to LV effect, the final sample has NC events.

iv.2 Timing corrections and systematic uncertainties

The operation of the T2K beam is not constant in time and varies with the hour of the day and season of the year. The effect of time-dependent changes in the neutrino event rate must be corrected since they can mimic an LV-oscillation signal or reduce the analysis sensitivity. Such effects can be separated into two distinct classes depending on whether they alter the neutrino beam itself or the INGRID detector. The first class consists of three time-dependent corrections considered for the neutrino beam:

  • Beam center variations during each run: Since the neutrino interaction rate itself is insufficient to estimate these variations, muons collected spill-by-spill with a muon detector just downstream of the decay volume Abe and others (T2K Collaboration) (2015) are used to estimate the beam center position. For each of the four run periods considered in this exposure, the beam center position as a function of LSP is estimated after correcting for tidal effects at the detector. These data are then used to extrapolate the position of the neutrino beam center, which is aligned with the muon direction, at INGRID. LSP-dependent corrections to observed event rate at INGRID due to shifts in the neutrino beam center are estimated using MC.

  • Beam center variation between runs: Changes in the average beam center position between run periods are evaluated using the INGRID neutrino data and a correction is estimated and applied as in the above.

  • Beam intensity variation between runs and non-uniform POT exposure as a function of LSP: A correction is applied to bring the event rate per POT in each LSP bin in line with the average for the entire run. The correction is applied for each event based on its run and sidereal phase. A further correction is applied to make the average event rate per POT of each run consistent with that of a reference run chosen to be near the end of the data taking period.

The second class of effects consists of three additional corrections to account for changes in the response of INGRID:

  • Event pile-up variations: Typically only single interactions in an INGRID module are reconstructed and other interactions in the same data acquisition timing window (one for each neutrino bunch) are lost (pile-up events). However, changes in the beam intensity affect the probability of multiple interactions within an INGRID reconstruction timing window. Accordingly, events at INGRID are corrected as a linear function of LSP to account for the variation in pile-up events with variations in the beam intensity. The number of lost pile-up events varies between 3% and 7% across the INGRID modules.

  • Dark noise variations: Variations in the temperature and humidity affect the MPPC dark rate, which in turn weakly affects the neutrino detection efficiency. The maximal variations of the dark rate with the sidereal time is . A correction to account for this efficiency variation has been applied linearly with the dark rate.

  • Variations in the photosensor gain: The MPPC gain is influenced by environmental changes, and the scintillator gain might decrease over time. Gain changes impact both the reconstruction and the analysis selection and are corrected using a sample of beam-induced muon interactions in the rock upstream of INGRID. The effect of variations in the charge at the minimum ionization peak of these muons is simulated in MC and used to correct the neutrino event rate. The size of the correction varies with LSP and does not exceed 1%.

The validity of the above corrections has been tested by separating the analysis data set into day and night subsamples. Though time-dependent differences are expected in the split samples due to, for instance, cooler temperatures at night or beamline maintenance during the day, the data should be consistent with one another when viewed in the LSP coordinate if the above corrections have been applied consistently. Figure 3 shows the day and night distributions as a function of LSP. The agreement between the day and night distribution is evaluated with a Pearson’s chi-squared test and a corresponding has been found. Data before and after all corrections also appear in the figure. Systematic errors for each of the corrections have been evaluated and are listed in Table 1. The total systematic error is , which is small when compared to the statistical error of the final sample, .

Figure 3: Distribution of reconstructed -like events per POT as a function of LSP. Data before (magenta) and after (black) corrections are shown together with the corrected sample additionally split into day (red) and night (blue) subsamples.
Source Systematic uncertainty (%)
Pile-up 0.01
MPPC dark noise 0.01
MPPC gain variation 0.06
Beam position 0.03
Beam intensity 0.05
Total systematic 0.08
Table 1: Summary of the systematic uncertainties induced from correcting for time dependent variations in the neutrino event rate. The beam position variation between and within run periods have been combined into a single entry in the table.

V Analysis methodology and results

The analysis of the final data sample is performed in two stages. First, the compatibility of the data with a null signal is studied using a fast Fourier transform (FFT) method (Section V.1). This method explicitly searches for a sidereal modulation and ultimately provides an estimate of the power of each Fourier mode from a potential signal. Then, constraints on the parameters appearing in Equation (1) are extracted using a likelihood method (Section V.2) that includes their correlations. Figure 4 shows examples of the expected LSP distribution for MC generated under three signal assumptions.

Figure 4: Distribution of the event rate as a function of LSP for three different assumed signal configurations: GeV (red), GeV (green), GeV (blue). The coefficients corresponding to oscillation () have been set to 0.

v.1 The Fast Fourier transform result

Expanding Equation (1) indicates that LV oscillations are described by four harmonic sidereal frequencies , and a constant term. The FFT Press (2007); Duhamel et al. (1990) method is most efficient for bins and the sensitivity of the current analysis is found to be optimal when . Data are therefore divided into 32 evenly spaced LSP bins for input into the FFT and the magnitudes of the four Fourier modes, , are then estimated. Note that the constant term is not considered in this study due to large uncertainties in the beam flux normalization. A detection threshold has been determined as the power in a Fourier mode for which 0.3% of MC experiments generated without LV effects shows higher power. For each mode this threshold corresponds to . The results of the fit to the data are shown in Table 2 together with a p-value estimating the likelihood that the observed power was produced by a statistical fluctuation of the null (no LV) hypothesis. All are below the detection threshold and indicate no evidence for a LV signal.

Fourier Mode Magnitude p-value
0.011 0.35
0.009 0.48
0.006 0.69
0.009 0.51
Table 2: Observed power in each Fourier mode from a fit to the data using the FFT method. A positive observation at would correspond to an observed power greater than 0.026 in any .

Constraints on the SME coefficients can be extracted with the FFT method Adamson et al. (2008); Diaz et al. (2009) under the assumption that the parameters above are uncorrelated. However, since the data sets are reduced to the four amplitudes and the relatively large number of parameters in the oscillation function, correlations are expected. Figure 5 shows the probability for data without LV to yield more power in the Fourier modes than the average expected for a LV signal as a function of the SME coefficients and . The parameters exhibit a high degree of anti-correlation, indicating that in the event of a null observation as above, using the FFT method without considering these correlations may lead to an underestimation of the parameter limits. As the parameters in Equation (1) are functions of these coefficients, they might be also expected to exhibit correlations. Accordingly, a likelihood method has been developed to fully incorporate these correlations when making parameter estimations.

Figure 5: Probability for the observed Fourier power in a null observation to exceed the expected power from a LV signal as a function of the and coefficients.

v.2 Likelihood analysis

Due to the large number of SME parameters Diaz et al. (2009) relative to the number of observables, this analysis does not estimate the and parameters but the , , , , () parameters from Equation (1) using a likelihood method that fully incorporates their correlations and the experimental uncertainties. However, since the impact of systematic errors is negligible (c.f. Table 1), only the statistical uncertainty in each LSP bin is considered here. Further, each parameter is assumed to be real valued. Sensitivity studies without this assumption showed no significant constraint on the complex phases of these parameters with the present data. Under these conditions, a simultaneous fit for ten real parameters using the data and binning from the previous section has been performed. Since the parameters are highly correlated, the contours and limits are not estimated assuming a profiling method, but instead using a likelihood marginalization which genuinely preserve their correlations Patrignani et al. (2016). This analysis assumes flat priors for all the parameters since no LV has been discovered so far. The results of the fit are shown in the Table 3.

Best fits -0.3 0.3 0.4 -1.2 2.0
C.L Limits 1.3 1.5 2.0 1.3 1.6
95% C.L Limits 3.0 3.2 3.8 2.6 3.1
95% C.L Sensitivity 2.5 2.7 4.3 3.5 3.5
Best fits -0.8 -0.4 -3.2 -0.4 1.1
C.L Limits 1.3 1.5 2.0 1.3 1.6
95% C.L Limits 3.0 3.2 3.8 2.6 3.1
95% C.L Sensitivity 2.5 2.7 4.3 3.5 3.5
Table 3: Best fit (BF) values with , and upper limit values on the LV model parameters using the likelihood method (in units of GeV). In the last row, the expected sensitivity is shown.

As expected from the FFT method, no indications of LV oscillations are found and upper limits are set for each parameter. Those limits are compared with the sensitivity obtained by determining the parameter absolute values for which of some MC experiments generated without LV effects shows higher absolute values. The contour limits are constructed following a constant method and are shown in Figure 6 for the and parameters that show important anti-correlations. While correlated-parameter analyses have been performed elsewhere Katori (2012), this is the first search to do so using all ten parameters simultaneously. The five harmonics in Equation (1) heavily correlate the ten parameters as shown in Figure 6. Neglecting the correlations between the parameters will lead an underestimation of the parameter limits. Since these correlations vary with the direction and position of each experiment, any comparison or combination of the limits found by different experiments requires to preserve these correlations.

Figure 6: Ten-coefficient fit result in the coefficient plane. The other parameters are marginalized over. The best fit point is marked in black, with , and credible intervals shown in red, green and blue, respectively.

Vi Conclusions

The T2K experiment has performed a search for Lorentz and CPT invariance violations using the INGRID on-axis near detector. Two complementary analysis methods have found no evidence of such symmetry violations for the energy, neutrino baseline, and data set used. Not only are the data consistent with an LSP-independent event rate based on a FFT analysis, but a likelihood analysis incorporating parameter correlations has corroborated this finding and yielded constraints on ten SME parameters.

Acknowledgements

We thank the J-PARC staff for superb accelerator performance. We thank the CERN NA61 Collaboration for providing valuable particle production data. We acknowledge the support of MEXT, Japan; NSERC (Grant No. SAPPJ-2014-00031), NRC and CFI, Canada; CEA and CNRS/IN2P3, France; DFG, Germany; INFN, Italy; National Science Centre (NCN) and Ministry of Science and Higher Education, Poland; RSF, RFBR, and MES, Russia; MINECO and ERDF funds, Spain; SNSF and SERI, Switzerland; STFC, UK; and DOE, USA. We also thank CERN for the UA1/NOMAD magnet, DESY for the HERA-B magnet mover system, NII for SINET4, the WestGrid and SciNet consortia in Compute Canada, and GridPP in the United Kingdom. In addition, participation of individual researchers and institutions has been further supported by funds from ERC (FP7), H2020 Grant No. RISE-GA644294-JENNIFER, EU; JSPS, Japan; Royal Society, UK; and the DOE Early Career program, USA.

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