1,799 research outputs found

    Understanding CP phase-dependent measurements at neutrino superbeams in terms of bi-rate graphs

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    We discuss the impact of the true value of the CP phase on the mass hierarchy, CP violation, and CP precision measurements at neutrino superbeams and related experiments. We we use a complete statistical experiment simulation including spectral information, systematics, correlations, and degeneracies to produce the results. However, since it is very complicated to understand the results in terms of a complete experiment simulation, we show the corresponding bi-rate graphs as useful tools to investigate the CP phase-dependencies qualitatively. Unlike bi-probability graphs, which are based upon oscillation probabilities, bi-rate graphs use the total event rates of two measurements simultaneously as a function of the CP phase. Since they allow error bars for direct quantitative estimates, they can be used for a direct comparison with a complete statistical experiment simulation. We find that one can describe the CP phase dependencies of the mentioned measurements at neutrino superbeam setups, as well as one can understand the role of the sgn(Δm312)\mathrm{sgn} (\Delta m_{31}^2)-degeneracy. As one of the most interesting results, we discuss the dependence of the CP precision measurement as a function of the CP phase itself, which leads to ``CP patterns''. It turns out that this dependence is rather strong, which means that one has to be careful when one is comparing the CP precisions of different experiments.Comment: Major revisions: Scope reduced and discussions simplified. Summary and conclusions unchanged. 14 pages, 4 figures. Final version to appear in PR

    Resolving degeneracies for different values of θ13\theta_{13}

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    We discuss options to resolve correlations and degeneracies with combinations of future neutrino long-baseline experiments. We use a logarithmic scale of sin22θ13\sin^2 2 \theta_{13} as a representation for a systematical classification of the experiments.Comment: 4 pages, Proceedings of NuFact 03, 5th International Workshop on Neutrino Factories & Superbeams, 5-11 June 2003, Columbia University, New Yor

    How astrophysical neutrino sources could be used for early measurements of neutrino mass hierarchy and leptonic CP phase

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    We discuss the possible impact of astrophysical neutrino flux measurements at neutrino telescopes on the neutrino oscillation program of reactor experiments and neutrino beams. We consider neutrino fluxes from neutron sources, muon damped sources, and pion sources, where we parameterize the input from these sources in terms of the flux ratio R=ϕμ/(ϕe+ϕτ)R=\phi_\mu/(\phi_e+\phi_\tau) which can be extracted from the muon track to shower ratio in a neutrino telescope. While it is difficult to obtain any information from this ratio alone, we demonstrate that the dependence on the oscillation parameters is very complementary to the one of reactor experiments and neutrino beams. We find that for large values of sin22θ13\sin^2 2 \theta_{13}, a measurement of R with a precision of about 20% or better may not only improve the measurement of the leptonic CP phase, but also help the determination of the mass hierarchy. In some cases, early information on δCP\delta_{CP} may even be obtained from Double Chooz and an astrophysical flux alone without the help of superbeams. For small values of sin22θ13\sin^2 2 \theta_{13}, we find that using the information from an astrophysical neutrino flux could eliminate the octant degeneracy better than reactor experiments and beams alone. Finally, we demonstrate that implementing an additional observable based on the electromagnetic to hadronic shower ratio at a neutrino telescope (such as at higher energies) could be especially beneficial for pion beam sources.Comment: Minor changes and additions, final version to appear in PRD. 32 pages, 15 figure

    Lectures on neutrino phenomenology

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    The fundamental properties of the lepton sector include the neutrino masses and flavor mixings. Both are difficult to observe because of the extremely small neutrino masses and neutrino-matter cross sections. In these lectures, we focus on the basic concepts for the determination of neutrino properties. We introduce neutrino oscillations as standard mechanism for neutrino flavor changes, and we discuss methods to measure the neutrino mass. Furthermore, we illustrate how precision measurements in neutrino oscillations will be performed in the future, and may even open a window to new physics properties, such as motivated by LHC physics. Finally, we discuss some applications of neutrinos in astrophysics, such as neutrino oscillations in the Sun. We also illustrate how neutrinos from extragalactic cosmic accelerators may be used for the determination of neutrino properties.Comment: 37 pages, 13 figures, 1 table. Lectures given at the Schladming Winter School 2010 "Masses and Constants"

    Optimization of a Very Low Energy Neutrino Factory for the Disappearance Into Sterile Neutrinos

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    We discuss short-baseline electron and muon neutrino disappearance searches into sterile neutrinos at a Very Low Energy Neutrino Factory (VLENF) with a muon energy between about two and four GeV. A lesson learned from reactor experiments, such as Double Chooz and Daya Bay, is to use near and far detectors with identical technologies to reduce the systematical errors. We therefore derive the physics results from a combined near-far detector fit and illustrate that uncertainties on cross sections x efficiencies can be eliminated in a self-consistent way. We also include the geometry of the setup, i.e., the extension of the decay straight and the muon decay kinematics relevant at the near detector, and we demonstrate that these affect the sensitivities for Delta m^2 > 30 eV^2, where oscillations take place already in the near detector. Compared to appearance searches, we find that the sensitivity depends on the locations of both detectors and the muon energy, where the near detector should be as close as possible to the source, and the far detector at about 500 to 800m. In order to exclude the currently preferred parameter region, at least 10^19 useful muon decays per polarity are needed for E_mu=2 GeV, or, alternatively, a higher muon energy can be used.Comment: 16 pages, 6 figure

    Neutrino mass hierarchy determination with IceCube-PINGU

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    We discuss the neutrino mass hierarchy determination with atmospheric neutrinos in PINGU (Precision IceCube Next Generation Upgrade), based on a simulation with the GLoBES software including the full three flavor framework and parameter degeneracy, and we compare it to long-baseline experiment options. We demonstrate that the atmospheric mass hierarchy sensitivity depends on the achievable experiment properties and we identify the main targets for optimization, whereas the impact of a large number of tested systematical errors turns out to be small. Depending on the values of theta_23, delta, and the true hierarchy, a 90% CL to 3sigma discovery after three years of operation seems conceivable. We also emphasize the synergy with existing beam and reactor experiments, driven by NOvA, such as the complementary coverage of the parameter space. Finally, we point out that a low intensity neutrino beam with a relatively short decay pipe could be used to determine the mass hierarchy with a sensitivity comparable to the LBNE experiment irrespective of the directional resolution of the detector.Comment: 22 pages, 9 figures, 1 table. Several clarifications, T2K data removed from main line of analysis. Version accepted for publication in Phys. Rev.