846 research outputs found

### Limits on Electron Neutrino Disappearance from the KARMEN and LSND electron neutrino - Carbon Cross Section Data

This paper presents a combined analysis of the KARMEN and LSND nu_e-carbon
cross section measurements within the context of a search for nu_e
disappearance at high Delta m^2. KARMEN and LSND were located at 17.7 m and
29.8 m respectively from the neutrino source, so the consistency of the two
measurements, as a function of antineutrino energy, sets strong limits on
neutrino oscillations. Most of the allowed region from the nu_e disappearance
analysis of the Gallium calibration data is excluded at >95% CL and the best
fit point is excluded at 3.6$\sigma$. Assuming CPT conservation, comparisons
are also made to the oscillation analyses of reactor antineutrino data.Comment: Published versio

### Using Reactors to Measure $\theta_{13}$

A next-generation neutrino oscillation experiment using reactor neutrinos
could give important information on the size of mixing angle $\theta_{13}$. The
motivation and goals for a new reactor measurement are discussed in the context
of other measurements using off-axis accelerator neutrino beams. The reactor
measurements give a clean measure of the mixing angle without ambiguities
associated with the size of the other mixing angles, matter effects, and
effects due to CP violation. The key question is whether a next-generation
experiment can reach the needed sensitivity goals to make a measurement for
$\sin^{2}2\theta_{13}$ at the 0.01 level. The limiting factors associated with
a reactor disappearance measurement are described with some ideas of how
sensitivities can be improved. Examples of possible experimental setups are
presented and compared with respect to cost and sensitivity

### Confronting the short-baseline oscillation anomalies with a single sterile neutrino and non-standard matter effects

We examine the MiniBooNE neutrino, MiniBooNE antineutrino and LSND
antineutrino data sets in a two-neutrino
$\stackrel{\tiny{(-)}}{\nu}_{\mu}\rightarrow\stackrel{\tiny{(-)}}{\nu}_e$
oscillation approximation subject to non-standard matter effects. We assume
those effects can be parametrized by an $L$-independent effective potential,
$V_s=\pm A_s$, experienced only by an intermediate, non-weakly-interacting
(sterile) neutrino state which we assume participates in the oscillation, where
$+/-$ corresponds to neutrino/antineutrino propagation. We discuss the
mathematical framework in which such oscillations arise in detail, and derive
the relevant oscillation probability as a function of the vacuum oscillation
parameters $\Delta m^2$ and $\sin^22\theta_{\mu e}$, and the matter effect
parameter $A_s$. We are able to successfully fit all three data sets, including
the MiniBooNE low energy excess, with the following best-fit model parameters:
$\Delta m^2=0.47$ eV$^2$, $\sin^22\theta_{\mu e}=0.010$, and
$A_s=2.0\times10^{-10}$ eV. The $\chi^2$-probability for the best fit
corresponds to 21.6%, to be compared to 6.8% for a fit where $A_s$ has been set
to zero, corresponding to a (3+1) sterile neutrino oscillation model. We find
that the compatibility between the three data sets corresponds to 17.4%, to be
compared to 2.3% for $A_s=0$. Finally, given the fit results, we examine
consequences for reactor, solar, and atmospheric oscillations. For this paper,
the presented model is empirically driven, but the results obtained can be
directly used to investigate various phenomenological interpretations such as
non-standard matter effects.Comment: 19 pages, 11 figures, 1 tabl

### Comparisons and Combinations of Reactor and Long-Baseline Neutrino Oscillation Measurements

We investigate how the data from various future neutrino oscillation
experiments will constrain the physics parameters for a three active neutrino
mixing model. The investigations properly account for the degeneracies and
ambiguities associated with the phenomenology as well as estimates of
experimental measurement errors. Combinations of various reactor measurements
with the expected J-PARC (T2K) and NuMI offaxis (Nova) data, both with and
without the increased flux associated with proton driver upgrades, are
considered. The studies show how combinations of reactor and offaxis data can
resolve degeneracies (e.g. the theta23 degeneracy) and give more precise
information on the oscillation parameters. A primary purpose of this
investigation is to establish the parameter space regions where CP violation
can be discovered and where the mass hierarchy can be determined. It is found
that such measurements, even with the augmented flux from proton driver
upgrades, demand sin^2 (2 theta13) be fairly large and in the range where it is
measurable by reactor experiments.Comment: 25 pages, 13 figures, fixed typos; 25 pages, 13 figures, updated
content, references; previous 22 pages, 12 figures, added references and
fixed reference display proble

### Precision Measurement of sin^2 theta_W at a Reactor

This paper presents a strategy for measuring sin^2 theta_W to ~1% at a
reactor-based experiment, using antineutrinos electron elastic scattering. This
error is comparable to the NuTeV, SLAC E158, and APV results on sin^2 theta_W,
but with substantially different contributions to the systematics. An improved
method for identifying antineutrino proton events, which serve both as a
background and as a normalization sample, is described. The measurement can be
performed using the near detector of the presently proposed reactor-based
oscillation experiments. We conclude that an absolute error of delta(sin^2
theta_W)=0.0019 may be achieved.Comment: To be Submitted to Phys. Rev.

### The LSND and MiniBooNE Oscillation Searches at High $\Delta m^2$

This paper reviews the results of the LSND and MiniBooNE experiments. The
primary goal of each experiment was to effect sensitive searches for neutrino
oscillations in the mass region with $\Delta m^2 \sim 1$ eV$^2$. The two
experiments are complementary, and so the comparison of results can bring
additional information with respect to models with sterile neutrinos. Both
experiments obtained evidence for $\bar \nu_\mu \rightarrow \bar \nu_e$
oscillations, and MiniBooNE also observed a $\nu_\mu \rightarrow \nu_e$ excess.
In this paper, we review the design, analysis, and results from these
experiments. We then consider the results within the global context of sterile
neutrino oscillation models. The final data sets require a more extended model
than the simple single sterile neutrino model imagined at the time that LSND
drew to a close and MiniBooNE began. We show that there are apparent
incompatibilities between data sets in models with two sterile neutrinos.
However, these incompatibilities may be explained with variations within the
systematic error. Overall, models with two (or three) sterile neutrinos seem to
succeed in fitting the global data, and they make interesting predictions for
future experiments.Comment: Posted with permission from the Annual Review of Nuclear and Particle
Science, Volume 63. \c{opyright} 2013 by Annual Reviews,
http://www.annualreviews.or

### Sterile Neutrino Fits to Short Baseline Neutrino Oscillation Measurements

This paper reviews short baseline oscillation experiments as interpreted
within the context of one, two, and three sterile neutrino models associated
with additional neutrino mass states in the ~1 eV range. Appearance and
disappearance signals and limits are considered. We show that fitting short
baseline data sets to a (3+3) model, defined by three active and three sterile
neutrinos, results in an overall goodness of fit of 67%, and a compatibility of
90% among all data sets -- to be compared to the compatibility of 0.043% and
13% for a (3+1) and a (3+2) model, respectively. While the (3+3) fit yields the
highest quality overall, it still finds inconsistencies with the MiniBooNE
appearance data sets; in particular, the global fit fails to account for the
observed MiniBooNE low-energy excess. Given the overall improvement, we
recommend using the results of (3+2) and (3+3) fits, rather than (3+1) fits,
for future neutrino oscillation phenomenology. These results motivate the
pursuit of further short baseline experiments, such as those reviewed in this
paper.Comment: Submitted to Advances in High Energy Physics Special Issue on
Neutrino Physic

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