3,735 research outputs found

    Exploring Neutrino Oscillations with Superbeams

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    We consider the medium- and long-baseline oscillation physics capabilities of intense muon-neutrino and muon-antineutrino beams produced using future upgraded megawatt-scale high-energy proton beams. In particular we consider the potential of these conventional neutrino ``superbeams'' for observing \nu_\mu\to\nu_e oscillations, determining the hierarchy of neutrino mass eigenstates, and measuring CP-violation in the lepton sector. The physics capabilities of superbeams are explored as a function of the beam energy, baseline, and the detector parameters. The trade-offs between very large detectors with poor background rejection and smaller detectors with excellent background rejection are illustrated. We find that it may be possible to observe \nu_\mu\to\nu_e oscillations with a superbeam provided that the amplitude parameter \sin^2 2\theta_{13} is larger than a few \times 10^{-3}. If \sin^2 2\theta_{13} is of order 10^{-2} or larger, then the neutrino mass hierarchy can be determined in long-baseline experiments, and if in addition the large mixing angle MSW solution describes the solar neutrino deficit then there is a small region of parameter space within which maximal CP-violation in the lepton sector would be observable in a low-energy medium-baseline experiment. We explicitly consider massive water Cherenkov and liquid argon detectors at superbeams with neutrino energies ranging from 1 GeV to 15 GeV, and baselines from 295 km to 9300 km. Finally, we compare the oscillation physics prospects at superbeams with the corresponding prospects at neutrino factories. The sensitivity at a neutrino factory to CP violation and the neutrino mass hierarchy extends to values of the amplitude parameter \sin^2 2\theta_{13} that are one to two orders of magnitude lower than at a superbeam.Comment: Revtex (singlespaced), 41 pages, uses epsf.sty, 12 postscript figures. Minor corrections and notation changes, expanded discussions, x-axis numbers added to Fig.9(a),(c). To be published in Phys. Rev.

    Matter Enhanced Neutrino Oscillations with a Realistic Earth Density Profile

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    We have investigated matter enhanced neutrino oscillations with a mantle-core-mantle step function and a realistic Earth matter density profile in both a two and a three neutrino scenario. We found that the realistic Earth matter density profile can be well approximated with the mantle-core-mantle step function and that there could be an influence on the oscillation channel ΜΌ→Μτ\nu_\mu \to \nu_\tau due to resonant enhancement of one of the mixing angles.Comment: 8 pages, 5 figures (PostScript), MPLA LaTe

    Masses and Mixings from Neutrino Beams pointing to Neutrino Telescopes

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    We discuss the potential to determine leading oscillation parameters, the value and the sign of \Delta m^2_{31}, as well as the magnitude of \sin^2 2\theta_{13} using a conventional wide band neutrino beam pointing to water or ice Cherenkov neutrino detectors known as ``Neutrino Telescopes''. We find that precision measurements of \Delta m^2_{31} and \theta_{23} are possible and that, even though it is not possible to discriminate between charges in the detector, there is a remarkably good sensitivity to the mixing angle \theta_{13} and the sign of \Delta m^2_{31}.Comment: 9 pages, 4 figure

    A Constraint on Yukawa-Coupling Unification from Lepton-Flavor Violating Processes

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    We present a new constraint on a lepton mixing matrix VV from lepton-flavor violating (LFV) processes in supersymmetric standard models with massive neutrinos. Here, we assume Yukawa-coupling unification fÎœ3≃ftopf_{\nu 3}\simeq f_{\rm top}, in which τ\tau-neutrino Yukawa coupling fÎœ3f_{\nu 3} is unified into top-quark Yukawa coupling ftopf_{\rm top} at the unification scale M∗≃3×1016M_*\simeq 3\times 10^{16} GeV. We show that the present experimental bound on Ό→eÎł\mu \to e \gamma decay already gives a stringent limit on the lepton mixing (typically V13<0.02V_{13}<0.02 for V23=1/2V_{23}=1/\sqrt{2}). Therefore, many existing neutrino-mass models are strongly constrained. Future improvement of bounds on LFV processes will provide a more significant impact on the models with the Yukawa-coupling unification. We also stress that a precise measurement of a neutrino mixing (VMNS)e3(V_{MNS})_{e3} in future neutrino experiments would be very important, since the observation of non-zero (VMNS)e3(V_{MNS})_{e3}, together with negative experimental results for the LFV processes, have a robust potential to exclude a large class of SUSY standard models with the Yukawa-coupling unification.Comment: 12 pages, 3 figure

    Assessing the impact of different liquid water permittivity models on the fit between model and observations

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    Permittivity models for microwave frequencies of liquid water below 0&thinsp;∘C (supercooled liquid water) are poorly constrained due to limited laboratory experiments and observations, especially for high microwave frequencies. This uncertainty translates directly into errors in retrieved liquid water paths of up to 80&thinsp;%. This study investigates the effect of different liquid water permittivity models on simulated brightness temperatures by using the all-sky assimilation framework of the Integrated Forecast System. Here, a model configuration with an improved representation of supercooled liquid water has been used. The comparison of five different permittivity models with the current one shows a small mean reduction in simulated brightness temperatures of at most 0.15&thinsp;K at 92&thinsp;GHz on a global monthly scale. During austral winter, differences occur more prominently in the storm tracks of the Southern Hemisphere and in the intertropical convergence zone with values of around 0.5 to 1.5&thinsp;K. Compared to the default Liebe (1989) approach, the permittivity models of Stogryn et al. (1995), Rosenkranz (2015) and Turner et al. (2016) all improve fits between observations and all-sky brightness temperatures simulated by the Integrated Forecast System. In cycling data assimilation these newer models also give small improvements in short-range humidity forecasts when measured against independent observations. Of the three best-performing models, the Stogryn et al. (1995) model is not quite as beneficial as the other two, except at 183&thinsp;GHz. At this frequency, Rosenkranz (2015) and Turner et al. (2016) look worse because they expose a scattering-related forward model bias in frontal regions. Overall, Rosenkranz (2015) is favoured due to its validity up to 1&thinsp;THz, which will support future submillimetre missions.</p

    Matter profile effect in neutrino factory

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    We point out that the matter profile effect --- the effect of matter density fluctuation on the baseline --- is very important to estimate the parameters in a neutrino factory with a very long baseline. To make it clear, we propose the method of the Fourier series expansion of the matter profile. By using this method, we can take account of both the matter profile effect and its ambiguity. For very long baseline experiment, such as L=7332km, in the analysis of the oscillation phenomena we need to introduce a new parameter a1 a_{1} --- the Fourier coefficient of the matter profile --- as a theoretical parameter to deal with the matter profile effects.Comment: 21 pages, 15 figure

    The effectiveness of interventions in workplace health promotion as to maintain the working capacity of health care personal

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    Background: The increasing proportion of elderly people with respective care requirements and within the total population stands against aging personnel and staff reduction in the field of health care where employees are exposed to high load factors. Health promotion interventions may be a possibility to improve work situations and behavior. Methods: A systematic literature search is conducted in 32 databases limited to English and German publications since 1990. Moreover, internet-searches are performed and the reference lists of identified articles are scanned. The selection of literature was done by two reviewers independently according to inclusion and exclusion criteria. Data extraction and tables of evidence are verified by a second expert just like the assessment of risk of bias by means of the Cochrane Collaboration’s tool. Results: We identified eleven intervention studies and two systematic reviews. There were three randomized controlled trials (RCT) and one controlled trial without randomization (CCT) on the improvement of physical health, four RCT and two CCT on the improvement of psychological health and one RCT on both. Study duration ranged from four weeks to two years and the number of participants included from 20 to 345, with a median of 56. Interventions and populations were predominantly heterogeneous. In three studies intervention for the improvement of physical health resulted in less complaints and increased strength and flexibility with statistically significant differences between groups. Regarding psychological health interventions lead to significantly decreased intake of analgesics, better stress management, coping with workload, communication skills and advanced training. Discussion: Taking into consideration the small to very small sample sizes, other methodological flaws like a high potential of bias and poor quality of reporting the validity of the results has to be considered as limited. Due to the heterogeneity of health interventions, study populations with differing job specializations and different lengths of study durations and follow-up periods, the comparison of results would not make sense. Conclusions: Further research is necessary with larger sample sizes, with a sufficient study duration and follow-up, with a lower risk of bias, by considering of relevant quality criteria and with better reporting in publications
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