217 research outputs found
Untangling CP Violation and the Mass Hierarchy in Long Baseline Experiments
In the overlap region, for the normal and inverted hierarchies, of the
neutrino-antineutrino bi-probability space for appearance,
we derive a simple identity between the solutions in the (, ) plane for the different hierarchies. The
parameter sets the scale of the
appearance probabilities at the atmospheric eV whereas controls the amount of CP
violation in the lepton sector. The identity between the solutions is that the
difference in the values of for the two hierarchies equals twice
the value of divided by the {\it critical} value
of . We apply this identity to the two proposed
long baseline experiments, T2K and NOA, and we show how it can be used to
provide a simple understanding of when and why fake solutions are excluded when
two or more experiments are combined. The identity demonstrates the true
complimentarity of T2K and NOA.Comment: 15 pages, Latex, 4 postscript figures. Submitted to New Journal of
Physics, ``Focus on Neutrino Physics'' issu
Synergies between the first-generation JHF-SK and NuMI superbeam experiments
We discuss synergies in the combination of the first-generation JHF to
Super-Kamiokande and NuMI off-axis superbeam experiments. With synergies we
mean effects which go beyond simply adding the statistics of the two
experiments. As a first important result, we do not observe interesting synergy
effects in the combination of the two experiments as they are planned right
now. However, we find that with minor modifications, such as a different NuMI
baseline or a partial antineutrino running, one could do much richer physics
with both experiments combined. Specifically, we demonstrate that one could,
depending on the value of the solar mass squared difference, either measure the
sign of the atmospheric mass squared difference or CP violation already with
the initial stage experiments. Our main results are presented in a way that can
be easily interpreted in terms of the forthcoming KamLAND result.Comment: 29 pages, 10 figure
Reactor Neutrino Experiments Compared to Superbeams
We present a detailed quantitative discussion of the measurement of the
leptonic mixing angle with a future reactor neutrino
oscillation experiment consisting of a near and far detector. We perform a
thorough analysis of the impact of various systematical errors and compare the
resulting physics potential to the one of planned first-generation superbeam
experiments. Furthermore, we investigate the complementarity of both types of
experiments. We find that, under realistic assumptions, a determination of
down to is possible with reactor experiments.
They are thus highly competitive to first-generation superbeams and may be able
to test on shorter timescales. In addition, we find that
the combination of a KamLAND-size reactor experiment with one or two superbeams
could substantially improve the ability to access the neutrino mass hierarchy
or the leptonic CP phase.Comment: Typo in Eq. (9) corrected. 36 pages, 12 figure
Precision on leptonic mixing parameters at future neutrino oscillation experiments
We perform a comparison of the different future neutrino oscillation
experiments based on the achievable precision in the determination of the
fundamental parameters theta_{13} and the CP phase, delta, assuming that
theta_{13} is in the range indicated by the recent Daya Bay measurement. We
study the non-trivial dependence of the error on delta on its true value. When
matter effects are small, the largest error is found at the points where CP
violation is maximal, and the smallest at the CP conserving points. The
situation is different when matter effects are sizable. As a result of this
effect, the comparison of the physics reach of different experiments on the
basis of the CP discovery potential, as usually done, can be misleading. We
have compared various proposed super-beam, beta-beam and neutrino factory
setups on the basis of the relative precision of theta_{13} and the error on
delta. Neutrino factories, both high-energy or low-energy, outperform
alternative beam technologies. An ultimate precision on theta_{13} below 3% and
an error on delta of < 7^{\circ} at 1 sigma (1 d.o.f.) can be obtained at a
neutrino factory.Comment: Minor changes, matches version accepted in JHEP. 30 pages, 9 figure
Clone flow analysis for a theory inspired Neutrino Experiment planning
The presence of several clone solutions in the simultaneous measurement of
() has been widely discussed in literature. In this letter
we write the analytical formulae of the clones location in the
() plane as a function of the physical input pair
(). We show how the clones move with changing
. The "clone flow" can be significantly different if computed
(naively) from the oscillation probabilities or (exactly) from the
probabilities integrated over the neutrino flux and cross-section.
Using our complete computation we compare the clone flow of a set of possible
future neutrino experiments: the CERN SuperBeam, BetaBeam and Neutrino Factory
proposals. We show that the combination of these specific BetaBeam and
SuperBeam does not help in solving the degeneracies. On the contrary, the
combination of one of them with the Neutrino Factory Golden and Silver channel
can be used, from a theoretical point of view, to solve completely the
eightfold degeneracy.Comment: 23 pages, using epsfi
Neutrino physics at accelerators
Present and future neutrino experiments at accelerators are mainly concerned
with understanding the neutrino oscillation phenomenon and its implications.
Here a brief account of neutrino oscillations is given together with a
description of the supporting data. Some current and planned accelerator
neutrino experiments are also explained.Comment: 23 pages, 24 figures. Talk given at the Corfu Summer Institute on
Elementary Particle Physics 200
Superbeams versus Neutrino Factories
We compare the physics potential of planned superbeams with the one of
neutrino factories. Therefore, the experimental setups as well as the most
relevant uncertainties and errors are considered on the same footing as much as
possible. We use an improved analysis including the full parameter
correlations, as well as statistical, systematical, and degeneracy errors.
Especially, degeneracies have so far not been taken into account in a numerical
analysis. We furthermore include external input, such as improved knowledge of
the solar oscillation parameters from the KamLAND experiment. This allows us to
determine the limiting uncertainties in all cases. For a specific comparison,
we choose two representatives of each class: For the superbeam, we take the
first conceivable setup, namely the JHF to SuperKamiokande experiment, as well
as, on a longer time scale, the JHF to HyperKamiokande experiment. For the
neutrino factory, we choose an initially conceivable setup and an advanced
machine. We determine the potential to measure the small mixing angle sin^2 2
theta_{13}, the sign of Delta m^2_{31}, and the leptonic CP phase \deltacp,
which also implies that we compare the limitations of the different setups. We
find interesting results, such as the complete loss of the sensitivity to the
sign of Delta m^2_{31} due to degeneracies in many cases.Comment: Revised version with JHF energy resolution corrected, discussion of
detector issues added (App. B), and references added. Summary and conclusions
unchanged. 51 pages, 28 figures, 4 table
Neutrino hierarchy from CP-blind observables with high density magnetized detectors
High density magnetized detectors are well suited to exploit the outstanding
purity and intensities of novel neutrino sources like Neutrino Factories and
Beta Beams. They can also provide independent measurements of leptonic mixing
parameters through the observation of atmospheric muon-neutrinos. In this
paper, we discuss the combination of these observables from a multi-kton iron
detector and a high energy Beta Beam; in particular, we demonstrate that even
with moderate detector granularities the neutrino mass hierarchy can be
determined for values greater than 4.Comment: 16 pages, 7 figures. Added a new section discussing systematic errors
(sec 5.2); sec.5.1 and 4 have been extended. Version to appear in EPJ
A minimal Beta Beam with high-Q ions to address CP violation in the leptonic sector
In this paper we consider a Beta Beam setup that tries to leverage at most
existing European facilities: i.e. a setup that takes advantage of facilities
at CERN to boost high-Q ions (8Li and 8B) aiming at a far detector located at L
= 732 Km in the Gran Sasso Underground Laboratory. The average neutrino energy
for 8Li and 8B ions boosted at \gamma ~ 100 is in the range E_\nu = [1,2] GeV,
high enough to use a large iron detector of the MINOS type at the far site. We
perform, then, a study of the neutrino and antineutrino fluxes needed to
measure a CP-violating phase delta in a significant part of the parameter
space. In particular, for theta_13 > 3 deg, if an antineutrino flux of 3 10^19
useful 8Li decays per year is achievable, we find that delta can be measured in
60% of the parameter space with 6 10^18 useful 8B decays per year.Comment: 19 pages, 10 figures, added references and corrected typo
Neutrino tomography - Learning about the Earth's interior using the propagation of neutrinos
Because the propagation of neutrinos is affected by the presence of Earth
matter, it opens new possibilities to probe the Earth's interior. Different
approaches range from techniques based upon the interaction of high energy
(above TeV) neutrinos with Earth matter, to methods using the MSW effect on the
neutrino oscillations of low energy (MeV to GeV) neutrinos. In principle,
neutrinos from many different sources (sun, atmosphere, supernovae, beams etc.)
can be used. In this talk, we summarize and compare different approaches with
an emphasis on more recent developments. In addition, we point out other
geophysical aspects relevant for neutrino oscillations.Comment: 22 pages, 9 figures. Proceedings of ``Neutrino sciences 2005:
Neutrino geophysics'', December 14-16, 2005, Honolulu, USA. Minor changes,
some references added. Final version to appear in Earth, Moon, and Planet
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