3,735 research outputs found
Exploring Neutrino Oscillations with Superbeams
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
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
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
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
We present a new constraint on a lepton mixing matrix from lepton-flavor
violating (LFV) processes in supersymmetric standard models with massive
neutrinos. Here, we assume Yukawa-coupling unification , in which -neutrino Yukawa coupling is unified into
top-quark Yukawa coupling at the unification scale GeV. We show that the present experimental bound on decay already gives a stringent limit on the lepton mixing (typically
for ). 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
in future neutrino experiments would be very important, since
the observation of non-zero , 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
Permittivity models for microwave frequencies of
liquid water below 0 âC (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 %. 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 K
at 92 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 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 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 THz, which will support future
submillimetre missions.</p
Matter profile effect in neutrino factory
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 ---
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
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 Collaborationâs 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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