1,323 research outputs found
Report of the Beyond the MSSM Subgroup for the Tevatron Run II SUSY/Higgs Workshop
There are many low-energy models of supersymmetry breaking parameters which
are motivated by theoretical and experimental considerations. Here, we discuss
some of the lesser-known theories of low-energy supersymmetry, and outline
their phenomenological consequences. In some cases, these theories have more
gauge symmetry or particle content than the Minimal Supersymmetric Standard
Model. In other cases, the parameters of the Lagrangian are unusual compared to
commonly accepted norms (e.g., Wino LSP, heavy gluino LSP, light gluino, etc.).
The phenomenology of supersymmetry varies greatly between the different models.
Correspondingly, particular aspects of the detectors assume greater or lesser
importance. Detection of supersymmetry and the determination of all parameters
may well depend upon having the widest possible view of supersymmetry
phenomenology.Comment: 78 pages, 49 figures, to appear in the Proceedings of the Tevatron
Run II SUSY/Higgs Workshop. Editor: J. F. Gunion; BTMSSM Convenors: M.
Chertok, H. Dreiner, G. Landsberg, J. F. Gunion, J.D. Well
The hidden sterile neutrino and the (2+2) sum rule
We discuss oscillations of atmospheric and solar neutrinos into sterile
neutrinos in the 2+2 scheme. A zeroth order sum rule requires equal
probabilities for oscillation into nu_s and nu_tau in the solar+atmospheric
data sample. Data does not favor this claim. Here we use scatter plots to
assess corrections of the zeroth order sum rule when (i) the 4 x 4 neutrino
mixing matrix assumes its full range of allowed values, and (ii) matter effects
are included. We also introduce a related "product rule". We find that the sum
rule is significantly relaxed, due to both the inclusion of the small mixing
angles (which provide a short-baseline contribution) and to matter effects. The
product rule is also dramatically altered. The observed relaxation of the sum
rule weakens the case against the 2+2 model and the sterile neutrino. To
invalidate the 2+2 model, a global fit to data with the small mixing angles
included seems to be required.Comment: 43 pages, 11 figures (same as v2, accidental replacement
Matter Effects on Neutrino Oscillations in Long Baseline Experiments
We calculate matter effects on neutrino oscillations relevant for long
baseline experiments. In particular, we compare the results obtained with
constant density along the neutrino path versus results obtained by
incorporating the actual density profiles in the Earth. We study the dependence
of the oscillation signal on both and on the angles in the
leptonic mixing matrix. We also comment on the influence of
on the oscillations. The results show quantitatively how, as a function of
these input parameters, matter effects can cause significant (25 %) changes in
the oscillation probabilities. An important conclusion is that matter effects
can be useful in amplifying certain neutrino oscillation signals and helping
one to obtain measurements of mixing parameters and the magnitude and sign of
.Comment: 26 pages, Latex, 17 postscript figures, published version, some
references adde
The atmospheric neutrino anomaly without maximal mixing?
We consider a pattern of neutrino masses in which there is an approximate
mass degeneracy between the two mass eigenstates most coupled to the
and flavour eigenstates. Earth-matter effects can lift this
degeneracy and induce an effectively maximal mixing between these two
generations. This occurs if 's contain comparable admixtures of the
degenerate eigenstates, even rather small ones. This provides an explanation of
the atmospheric neutrino anomaly in which the {\it ab initio} introduction of a
large mixing angle is not required. To test this possibility we perform a novel
and detailed analysis of the 52 kiloton-year SuperKamiokande data, and we find
that in a large region of parameter space the corresponding confidence levels
are excellent. The most recent results from the Chooz reactor experiment,
however, severely curtail this region, so that the conventional scenario with
nearly maximal mixing angles --which we also analyse in detail-- is supported
by the data.Comment: Some relevant references added and a misprint correcte
Four--Neutrino Oscillation Solutions of the Solar Neutrino Problem
We present an analysis of the neutrino oscillation solutions of the solar
neutrino problem in the framework of four-neutrino mixing where a sterile
neutrino is added to the three standard ones. We perform a fit to the full data
set corresponding to the 825-day Super-Kamiokande data sample as well as to
Chlorine, GALLEX and SAGE and Kamiokande experiments. In our analysis we use
all measured total event rates as well as all Super-Kamiokande data on the
zenith angle dependence and the recoil electron energy spectrum. We consider
both transitions via the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism as well
as oscillations in vacuum (just-so) and find the allowed solutions for
different values of the additional mixing angles. This framework permits
transitions into active or sterile neutrinos controlled by the additional
parameter . We discuss the
maximum allowed values of this additional mixing parameter for the different
solutions.Comment: 28 pages Latex file using RevTeX. 8 postscript figures included
(bitmapped for compression). Detailed explanation of criterion 3 and lower
two graphs of Fig. 8. Misprints corrected in table II.A full version of the
paper can be found at http://ific.uv.es/~penya/papers/four
Auditory sensitivity in aquatic animals
© 2016 Acoustical Society of America. A critical concern with respect to marine animal acoustics is the issue of hearing "sensitivity," as it is widely used as a criterion for the onset of noise-induced effects. Important aspects of research on sensitivity to sound by marine animals include: uncertainties regarding how well these species detect and respond to different sounds; the masking effects of man-made sounds on the detection of biologically important sounds; the question how internal state, motivation, context, and previous experience affect their behavioral responses; and the long-term and cumulative effects of sound exposure. If we are to better understand the sensitivity of marine animals to sound we must concentrate research on these questions. In order to assess population level and ecological community impacts new approaches can possibly be adopted from other disciplines and applied to marine fauna
Status of four-neutrino mass schemes: a global and unified approach to current neutrino oscillation data
We present a unified global analysis of neutrino oscillation data within the
framework of the four-neutrino mass schemes (3+1) and (2+2). We include all
data from solar and atmospheric neutrino experiments, as well as information
from short-baseline experiments including LSND. If we combine only solar and
atmospheric neutrino data, (3+1) schemes are clearly preferred, whereas
short-baseline data in combination with atmospheric data prefers (2+2) models.
When combining all data in a global analysis the (3+1) mass scheme gives a
slightly better fit than the (2+2) case, though all four-neutrino schemes are
presently acceptable. The LSND result disfavors the three-active neutrino
scenario with only and at 99.9% CL with
respect to the four-neutrino best fit model. We perform a detailed analysis of
the goodness of fit to identify which sub-set of the data is in disagreement
with the best fit solution in a given mass scheme.Comment: 32 pages, 8 Figures included, REVTeX4.Improved discussion in sec. XI,
references added, version accepted by Phys. Rev.
Can R-parity violation explain the LSND data as well?
The recent Super-Kamiokande data now admit only one type of mass hierarchy in
a framework with three active and one sterile neutrinos. We show that neutrino
masses and mixings generated by R-parity-violating couplings, with values
within their experimental upper limits, are capable of reproducing this
hierarchy, explaining all neutrino data particularly after including the LSND
results.Comment: 7 pages, Latex, 3 PS figures; in v2 a few clarifying remarks included
and two references added (to appear in Physical Review D
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