We report the results of a search for νe appearance in a νµ beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of 8.2 × 10 20 protons on the NuMI target at Fermilab, we find that 2 sin 2 (θ23) sin 2 (2θ13) < 0.12 (0.20) at 90% confidence level for δ=0 and the normal (inverted) neutrino mass hierarchy, with a best fit of 2 sin 2 (θ23) sin 2 (2θ13) = 0.041−0.031 (0.079−0.053 ). The θ13=0 hypothesis is disfavored by the MINOS data at the 89% confidence level.PACS numbers: 14.60. Pq, 14.60.Lm, arXiv:1108.0015v1 [hep-ex] 29 Jul 2011 2 It has been experimentally established that neutrinos undergo flavor change as they propagate [1][2][3][4][5][6][7]. This phenomenon is well-described by three-flavor neutrino oscillations, characterized by the spectrum of neutrino masses together with the elements of the PMNS mixing matrix [8]. This matrix is often parametrized by three Euler angles θ ij and a CP-violating phase δ. While θ 12 and θ 23 are known to be large [1,4,6], θ 13 appears to be relatively small [9][10][11][12][13], with the tightest limits so far coming from the CHOOZ [10] and MINOS [12] experiments. The T2K collaboration has recently reported indications of a nonzero value for θ 13 at the 2.5σ confidence level (C.L.) [14]. This letter reports new θ 13 constraints from the MINOS experiment, using an increased data set and significant improvements to the analysis.MINOS is a two-detector long-baseline neutrino oscillation experiment situated along the NuMI neutrino beamline [15]. The 0.98-kton Near Detector (ND) is located on-site at Fermilab, 1.04 km downstream of the NuMI target. The 5.4-kton Far Detector (FD) is located 735 km downstream in the Soudan Underground Laboratory. The two detectors have nearly identical designs, each consisting of alternating layers of steel (2.54 cm thick) and plastic scintillator (1 cm). The scintillator layers are constructed from optically isolated, 4.1 cm wide strips that serve as the active elements of the detectors. The strips are read out via optical fibers and multi-anode photomultiplier tubes. Details can be found in Ref. [16].The data used in this analysis come from an exposure of 8.2×1020 protons on the NuMI target. The corresponding neutrino events in the ND have an energy spectrum that peaks at 3 GeV and a flavor composition of 91.7% ν µ , 7.0% ν µ , and 1.3% ν e +ν e , as estimated by beamline and detector Monte Carlo (MC) simulations, with additional constraints from MINOS ND data and external measurements [6,17]. The two-detector arrangement and the relatively small intrinsic ν e component make this analysis rather insensitive to beam uncertainties. Neutrino-nucleus and final-state interactions are simulated using NEUGEN3 [18], and particle propagation and detector response are simulated with GEANT3 [19].MINOS is sensitive to θ 13 through ν µ → ν e oscillations. To leading order, the probability for this oscillation mode is given bywhere ∆m 2 32 (in units of eV 2 ) and θ 23 are the dominant atmospheric oscillation...

and comprise 7.482 × 10 20 protons on target in neutrino mode, which yielded in the far detector 32 e-like and 135 μ-like events, and 7.471 × 10 20 protons on target in antineutrino mode, which yielded 4 e-like and 66 μ-like events. Reactor measurements of sin 2 2θ 13 have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase δ CP spans the range (−3.13, −0.39) for normal mass ordering. The CP conservation hypothesis (δ CP ¼ 0, π) is excluded at 90% C.L.

We report on νe andνe appearance in νµ andνµ beams using the full MINOS data sample. The comparison of these νe andνe appearance data at a 735 km baseline with θ13 measurements by reactor experiments probes δ, the θ23 octant degeneracy, and the mass hierarchy. This analysis is the first use of this technique and includes the first accelerator long-baseline search forνµ →νe. Our data disfavor 31% (5%) of the three-parameter space defined by δ, the octant of the θ23, and the mass hierarchy at the 68% (90%) C.L. We measure a value of 2sin 2 (2θ13)sin 2 (θ23) that is consistent with reactor experiments. 2PACS numbers: 14.60. Pq, 14.60.Lm, The neutrino oscillation phenomenon is successfully modeled by a theory of massive neutrino eigenstates that are different from the neutrino flavor eigenstates. These sets of eigenstates are related by the PMNS matrix [1] which is commonly parameterized by three angles, θ ij , and a CP-violating phase, δ.The values of θ 12 and θ 23 have been measured [2-4] with indications that θ 23 is not maximal [5][6][7]. The final angle, θ 13 , is now known to have a nonzero value from measurements by reactor experiments [8][9][10], the measurement by the T2K [11] accelerator experiment, and from earlier MINOS results [12,13].Despite these accomplishments, the value of δ is still unknown, as is the ordering of the neutrino masses, which is referred to as the neutrino mass hierarchy. Much of the attention in the neutrino community is now focused on resolving these unknowns. The mass hierarchy is not only a fundamental property of neutrinos but also has a direct impact on the ability of neutrinoless double beta decay searches to state definitively whether the neutrino is its own antiparticle [14]. Reactor experiments make a pure measurement of θ 13 , whereas the ν µ → ν e and ν µ →ν e appearance probabilities measured by accelerator experiments such as MINOS depend on the value of δ and sin 2 (θ 23 ). In addition, the long-baseline of MI-NOS means that interactions between neutrinos and the matter of the Earth make the appearance probabilities dependent on the neutrino mass hierarchy [15,16].We report the result from the search for ν e (ν e ) appearance in a ν µ (ν µ ) beam using the full MINOS data sample. This result uses an exposure of 10.6 × 10 20 protons-ontarget taken with a ν beam and an exposure of 3.3 × 10 20 protons-on-target taken with aν beam. The neutrino sample is 30% larger than the sample used for the previous MINOS results on this topic [13]. This analysis represents the first long-baseline search forν µ →ν e appearance and places new constraints on θ 13 and on a combination of δ, θ 23 , and the neutrino mass hierarchy.In the MINOS experiment [17], neutrino oscillation is studied with the NuMI beamline [18] by measuring neutrino interactions in two detectors. The Near Detector (ND), which has a fiducial mass of 29 tons, is at a distance of 1.04 km from the production target and is used to determine the composition of the beam before the neutrinos have oscillated. The Far Detector...

An analysis of atmospheric neutrino data from all four run periods of Super-Kamiokande optimized for sensitivity to the neutrino mass hierarchy is presented. Confidence intervals for Δm 2 32 , sin 2 θ 23 , sin 2 θ 13 and δ CP are presented for normal neutrino mass hierarchy and inverted neutrino mass hierarchy hypotheses, based on atmospheric neutrino data alone. Additional constraints from reactor data on θ 13 and from published binned T2K data on muon neutrino disappearance and electron neutrino appearance are added to the atmospheric neutrino fit to give enhanced constraints on the above parameters. Over the range of parameters allowed at 90% confidence level, the normal mass hierarchy is favored by between 91.9% and 94.5% based on the combined Super-Kamiokande plus T2K result.

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