14,885 research outputs found
The Effects of Inlet Flow Modification on Cavitating Inducer Performance
This paper explores the effect of inlet flow modification on the cavitating and noncavitating performance of two cavitating inducers, one of simple helical design and the other a model of the low-pressure LOX pump in the Space Shuttle Main Engine. The modifications were generated by sections of honeycomb, both uniform and nonuniform. Significant improvement in the performance over a wide range of flow coefficients resulted from the use of either honeycomb section. Measurements of the axial and swirl velocity profiles of the flows entering the inducers were made in order to try to understand the nature of the inlet flow and the manner in which it is modified by the honeycomb sections
Global status of neutrino oscillation parameters after Neutrino-2012
Here we update the global fit of neutrino oscillations in arXiv:1103.0734 and
arXiv:1108.1376 including the recent measurements of reactor antineutrino
disappearance reported by the Double Chooz, Daya Bay and RENO experiments,
together with latest MINOS and T2K appearance and disappearance results, as
presented at the Neutrino-2012 conference. We find that the preferred global
fit value of is quite large: for
normal and inverted neutrino mass ordering, with now excluded
at more than 10. The impact of the new measurements over
the other neutrino oscillation parameters is discussed as well as the role of
the new long-baseline neutrino data and the atmospheric neutrino analysis in
the determination of a non-maximal atmospheric angle .Comment: Note added, matches published version in Physical Review
Neutrino oscillations refitted
Here we update our previous global fit of neutrino oscillations by including
the recent results which have appeared since the Neutrino-2012 conference.
These include the measurements of reactor anti-neutrino disappearance reported
by Daya Bay and RENO, together with latest T2K and MINOS data including both
disappearance and appearance channels. We also include the revised results from
the third solar phase of Super-Kamiokande, SK-III, as well as new solar results
from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred
global determination of the atmospheric angle is consistent with
maximal mixing. We also determine the impact of the new data upon all the other
neutrino oscillation parameters with emphasis on the increasing sensitivity to
the CP phase, thanks to the interplay between accelerator and reactor data. In
the appendix we present the updated results obtained after the inclusion of new
reactor data presented at the Neutrino 2014 conference. We discuss their impact
on the global neutrino analysis.Comment: 13 pages, 5 figures, 2 tables. An appendix providing updated results
after Neutrino-2014 Conference is added. Matches published version in
Physical Review
Neutralino Phenomenology at LEP2 in Supersymmetry with Bilinear Breaking of R-parity
We discuss the phenomenology of the lightest neutralino in models where an
effective bilinear term in the superpotential parametrizes the explicit
breaking of R-parity. We consider supergravity scenarios where the lightest
supersymmetric particle (LSP) is the lightest neutralino and which can be
explored at LEP2. We present a detailed study of the LSP decay properties and
general features of the corresponding signals expected at LEP2. We also
contrast our model with gauge mediated supersymmetry breaking.Comment: 21 pages, Latex, uses axodraw.sty (included), 13 figures included as
ps- and eps-files, figures slightly changed after bug-fixing, comparison with
GMSB and a few references added, version to appear in NP
Bound-state dark matter with Majorana neutrinos
We propose a simple scenario in which dark matter (DM) emerges as a stable
neutral hadronic thermal relics, its stability following from an exact
symmetry. Neutrinos pick up radiatively induced
Majorana masses from the exchange of colored DM constituents. There is a common
origin for both dark matter and neutrino mass, with a lower bound for
neutrinoless double beta decay. Direct DM searches at nuclear recoil
experiments will test the proposal, which may also lead to other
phenomenological signals at future hadron collider and lepton flavour violation
experiments.Comment: 9 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1803.0852
Calculable inverse-seesaw neutrino masses in supersymmetry
We provide a scenario where naturally small and calculable neutrino masses
arise from a supersymmetry breaking renormalization-group-induced vacuum
expectation value. We adopt a minimal supergravity scenario without ad hoc
supersymmetric mass parameters. The lightest supersymmetric particle can be an
isosinglet scalar neutrino state, potentially viable as WIMP dark matter
through its Higgs new boson coupling. The scenario leads to a plethora of new
phenomenological implications at accelerators including the Large Hadron
Collider.Comment: LaTeX, 5 pages, 4 figures. Comments and references added. Final
version to appear in PR
Lepton flavor violation and non-unitary lepton mixing in low-scale type-I seesaw
Within low-scale seesaw mechanisms, such as the inverse and linear seesaw,
one expects (i) potentially large lepton flavor violation (LFV) and (ii)
sizeable non-standard neutrino interactions (NSI). We consider the interplay
between the magnitude of non-unitarity effects in the lepton mixing matrix, and
the constraints that follow from LFV searches in the laboratory. We find that
NSI parameters can be sizeable, up to percent level in some cases, while LFV
rates, such as that for \mu -> e \gamma, lie within current limits, including
the recent one set by the MEG collaboration. As a result the upcoming long
baseline neutrino experiments offer a window of opportunity for complementary
LFV and weak universality tests.Comment: 14 pages, 14 composite figures and 1 table. v2: minor changes,
references added. Accepted for publication in JHE
Probing neutrino transition magnetic moments with coherent elastic neutrino-nucleus scattering
We explore the potential of current and next generation of coherent elastic
neutrino-nucleus scattering (CENS) experiments in probing neutrino
electromagnetic interactions. On the basis of a thorough statistical analysis,
we determine the sensitivities on each component of the Majorana neutrino
transition magnetic moment (TMM), , that
follow from low-energy neutrino-nucleus experiments. We derive the sensitivity
to neutrino TMM from the first CENS measurement by the COHERENT
experiment, at the Spallation Neutron Source. We also present results for the
next phases of COHERENT using HPGe, LAr and NaI[Tl] detectors and for reactor
neutrino experiments such as CONUS, CONNIE, MINER, TEXONO and RED100. The role
of the CP violating phases in each case is also briefly discussed. We conclude
that future CENS experiments with low-threshold capabilities can improve
current TMM limits obtained from Borexino data.Comment: 25 pages, 8 figures, 2 tables, analysis updated; conclusions
unchanged; references added; matches published versio
On the description of non-unitary neutrino mixing
Neutrino oscillations are well established and the relevant parameters
determined with good precision, except for the CP phase, in terms of a unitary
lepton mixing matrix. Seesaw extensions of the Standard Model predict unitarity
deviations due to the admixture of heavy isosinglet neutrinos. We provide a
complete description of the unitarity and universality deviations in the light
neutrino sector. Neutrino oscillation experiments involving electron or muon
neutrinos and anti-neutrinos are fully described in terms of just three new
real parameters and a new CP phase, in addition to the ones describing
oscillations with unitary mixing. Using this formalism we describe the
implications of non-unitarity for neutrino oscillations and summarize the
model-independent constraints on heavy neutrino couplings that arise from
current experiments.Comment: 28 pages, 8 figures, typos corrected, modified bounds on
non-unitarity parameters, new figs 3 and
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