22 research outputs found

    Search for short baseline nu(e) disappearance with the T2K near detector

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    8 pages, 6 figures, submitted to PRD rapid communication8 pages, 6 figures, submitted to PRD rapid communicationWe thank the J-PARC staff for superb accelerator performance and the CERN NA61 collaboration for providing valuable particle production data. We acknowledge the support of MEXT, Japan; NSERC, NRC and CFI, Canada; Commissariat `a l’Energie Atomique and Centre National de la Recherche Scientifique–Institut National de Physique Nucle´aire et de Physique des Particules, France; DFG, Germany; INFN, Italy; National Science Centre (NCN), Poland; Russian Science Foundation, RFBR and Ministry of Education and Science, Russia; MINECO and European Regional Development Fund, Spain; Swiss National Science Foundation and State Secretariat for Education, Research and Innovation, 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, GridPP, UK. In addition participation of individual researchers and institutions has been further supported by funds from ERC (FP7), EU; JSPS, Japan; Royal Society, UK; DOE Early Career program, USA

    Measurement of the electron neutrino charged-current interaction rate on water with the T2K ND280 pi(0) detector

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    10 pages, 6 figures, Submitted to PRDhttp://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.112010© 2015 American Physical Society11 pages, 6 figures, as accepted to PRD11 pages, 6 figures, as accepted to PRD11 pages, 6 figures, as accepted to PR

    Measurement of muon antineutrino oscillations with an accelerator-produced off-axis beam

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    T2K reports its first measurements of the parameters governing the disappearance of νμ\overline{\nu}_\mu in an off-axis beam due to flavour change induced by neutrino oscillations. The quasi-monochromatic νμ\overline{\nu}_\mu beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the νμ\overline{\nu}_\mu survival probability is expected to be minimal. Using a dataset corresponding to 4.01×10204.01 \times 10^{20} protons on target, 3434 fully contained μ\mu-like events were observed. The best-fit oscillation parameters are: sin2(θ23)=0.45\sin^2 (\overline{\theta}_{23}) = 0.45 and Δm322=2.51×103|\Delta\overline{m}^2_{32}| = 2.51 \times 10^{-3} eV2^2 with 68% confidence intervals of 0.38 - 0.64 and 2.26 - 2.80 (×103\times 10^{-3} eV2^2) respectively. These world-leading results are in agreement with existing anti-neutrino parameter measurements and also with the νμ\nu_\mu disappearance parameters measured by T2K

    Measurement of double-differential muon neutrino charged-current interactions on C8H8 without pions in the final state using the T2K off-axis beam

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    We report the measurement of muon neutrino charged-current interactions on carbon without pions in the final state at the T2K beam energy using 5.734×1020 protons on target. For the first time the measurement is reported as a flux-integrated, double-differential cross section in muon kinematic variables (cosθμ, pμ), without correcting for events where a pion is produced and then absorbed by final state interactions. Two analyses are performed with different selections, background evaluations and cross-section extraction methods to demonstrate the robustness of the results against biases due to model-dependent assumptions. The measurements compare favorably with recent models which include nucleon-nucleon correlations but, given the present precision, the measurement does not distinguish among the available models. The data also agree with Monte Carlo simulations which use effective parameters that are tuned to external data to describe the nuclear effects. The total cross section in the full phase space is σ=(0.417±0.047(syst)±0.005(stat))×10-38 cm2 nucleon-1 and the cross section integrated in the region of phase space with largest efficiency and best signal-over-background ratio (cosθμ>0.6 and pμ>200 MeV) is σ=(0.202±0.036(syst)±0.003(stat))×10-38 cm2 nucleon-1

    Measurement of the muon neutrino inclusive charged-current cross section in the energy range of 1-3 GeV with the T2K INGRID detector

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    We report a measurement of the ν μ-nucleus inclusive charged-current cross section (=σ cc) on iron using data from the INGRID detector exposed to the J-PARC neutrino beam. The detector consists of 14 modules in total, which are spread over a range of off-axis angles from 0° to 1.1°. The variation in the neutrino energy spectrum as a function of the off-axis angle, combined with event topology information, is used to calculate this cross section as a function of neutrino energy. The cross section is measured to be σ cc (1.1  GeV)=1.10±0.15 (10 −38   cm 2 /nucleon), σ cc (2.0  GeV)=2.07±0.27 (10 −38   cm 2 /nucleon), and σ cc (3.3  GeV)=2.29±0.45 (10 −38   cm 2 /nucleon), at energies of 1.1, 2.0, and 3.3 GeV, respectively. These results are consistent with the cross section calculated by the neutrino interaction generators currently used by T2K. More importantly, the method described here opens up a new way to determine the energy dependence of neutrino-nucleus cross sections

    Measurement of coherent π+ production in low energy neutrino-Carbon scattering

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    International audienceWe report the first measurement of the flux-averaged cross section for charged current coherent π+ production on carbon for neutrino energies less than 1.5 GeV to a restricted final state phase space region in the T2K near detector, ND280. Comparisons are made with predictions from the Rein-Sehgal coherent production model and the model by Alvarez-Ruso {\it et al.}, the latter representing the first implementation of an instance of the new class of microscopic coherent models in a neutrino interaction Monte Carlo event generator. This results contradicts the null results reported by K2K and SciBooNE in a similar neutrino energy region

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

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    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 by 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 1020 at the GeV scale

    First Measurement of the Muon Neutrino Charged Current Single Pion Production Cross Section on Water with the T2K Near Detector

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    The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies ∼0.8  GeV. The differential measurements are presented as a function of the muon and pion kinematics, in the restricted phase space defined by pπ+>200  MeV/c, pμ>200  MeV/c, cos(θπ+)>0.3 and cos(θμ)>0.3. The total flux integrated νμ charged current single positive pion production cross section on water in the restricted phase space is measured to be ⟨σ⟩ϕ=4.25±0.48(stat)±1.56(syst)×10-40  cm2/nucleon. The total cross section is consistent with the NEUT prediction (5.03×10-40  cm2/nucleon) and 2σ lower than the GENIE prediction (7.68×10-40  cm2/nucleon). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but overestimates the overall cross section normalization.The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies 0.8{\sim}0.8 GeV. The differential measurements are presented as a function of muon and pion kinematics, in the restricted phase-space defined by pπ+>200p_{\pi^+}>200MeV/c, pμ>200p_{\mu^-}>200MeV/c, cosθπ+>0.3\cos \theta_{\pi^+}>0.3 and cosθμ>0.3\cos \theta_{\mu^-}>0.3. The total flux integrated νμ\nu_\mu charged current single positive pion production cross section on water in the restricted phase-space is measured to be σϕ=4.25±0.48(stat)±1.56(syst)×1040cm2/nucleon\langle\sigma\rangle_\phi=4.25\pm0.48 (\mathrm{stat})\pm1.56 (\mathrm{syst})\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}. The total cross section is consistent with the NEUT prediction (5.03×1040cm2/nucleon5.03\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}) and 2σ\sigma lower than the GENIE prediction (7.68×1040cm2/nucleon7.68\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but over-estimates the overall cross section normalization

    Upper bound on neutrino mass based on T2K neutrino timing measurements

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    The Tokai to Kamioka (T2K) long-baseline neutrino experiment consists of a muon neutrino beam, produced at the J-PARC accelerator, a near detector complex and a large 295km distant far detector. The present work utilizes the T2K event timing measurements at the near and far detectors to study neutrino time of flight as function of derived neutrino energy. Under the assumption of a relativistic relation between energy and time of flight, constraints on the neutrino rest mass can be derived. The sub-GeV neutrino beam in conjunction with timing precision of order tens of ns provide sensitivity to neutrino mass in the few MeV/c2c^2 range. We study the distribution of relative arrival times of muon and electron neutrino candidate events at the T2K far detector as a function of neutrino energy. The 90% C.L. upper limit on the mixture of neutrino mass eigenstates represented in the data sample is found to be m$_{\nu}^

    Measurement of the nu(mu) charged-current quasielastic cross section on carbon with the ND280 detector at T2K

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    The Charged-Current Quasi-Elastic (CCQE) interaction, νl + n → l − + p, is the dominant CC process at Eν ∼ 1 GeV and contributes to the signal in accelerator-based long-baseline neutrino oscillation experiments operating at intermediate neutrino energies. This paper reports a measurement by the T2K experiment of the νµ CCQE cross section on a carbon target with the off-axis detector based on the observed distribution of muon momentum (pµ) and angle with respect to the incident neutrino beam (θµ). The flux-integrated CCQE cross section was measured to be hσi = (0.83 ± 0.12) × 10−38 cm2 . The energy dependence of the CCQE cross section is also reported. The axial mass, MQE A , of the dipole axial form factor was extracted assuming the Smith-Moniz CCQE model with a relativistic Fermi gas nuclear model. Using the absolute (shapeonly) pµ-cosθµ distribution, the effective M QE A parameter was measured to be 1.26+0.21 −0.18 GeV/c2 (1.43+0.28 −0.22 GeV/c2 )
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