9,263 research outputs found
Ogus realization of 1-motives
After introducing the Ogus realization of 1-motives we prove that it is a
fully faithful functor. More precisely, following a framework introduced by
Ogus, considering an enriched structure on the de Rham realization of 1-motives
over a number field, we show that it yields a full functor by making use of an
algebraicity theorem of Bost
Method to measure off-axis displacements based on the analysis of the intensity distribution of a vortex beam
We study the properties of the Fraunhofer diffraction patterns produced by
Gaussian beams crossing spiral phase plates. We show, both analytically and
numerically, that off-axis displacements of the input beam produce asymmetric
diffraction patterns. The intensity profile along the direction of maximum
asymmetry shows two different peaks. We find that the intensity ratio between
these two peaks decreases exponentially with the off-axis displacement of the
incident beam, the decay being steeper for higher strengths of the optical
singularity of the spiral phase plate. We analyze how this intensity ratio can
be used to measure small misalignments of the input beam with a very high
precision.Comment: 8 pages, 4 figures. Accepted for publication in PR
Novel spectral kurtosis technology for adaptive vibration condition monitoring of multi-stage gearboxes
In this paper, the novel wavelet spectral kurtosis (WSK) technique is applied for the early diagnosis of gear tooth faults. Two variants of the wavelet spectral kurtosis technique, called variable resolution WSK and constant resolution WSK, are considered for the diagnosis of pitting gear faults. The gear residual signal, obtained by filtering the gear mesh frequencies, is used as the input to the SK algorithm. The advantages of using the wavelet-based SK techniques when compared to classical Fourier transform (FT)-based SK is confirmed by estimating the toothwise Fisher's criterion of diagnostic features. The final diagnosis decision is made by a three-stage decision-making technique based on the weighted majority rule. The probability of the correct diagnosis is estimated for each SK technique for comparison. An experimental study is presented in detail to test the performance of the wavelet spectral kurtosis techniques and the decision-making technique
Dairy production in urban and periurban area of Extrême-Nord in Cameroon: milk yield and microbial contamination
Local dairy production plays a very important role in developing countries in order to promote the health status of the population. To determine the weight and the hygiene level of milk products, available in the market of the capital city of the Extrême-Nord region, a survey on the milk yield and microbial contamination was developed. Milk samples from 89 dairy farmers in the urban and periurban area of Maroua, divided in 11 groups, matching the Groupe d'Initiative Commune (groups of common interest - GICs), were analyzed for yield, pH value, temperature, density and microbial contamination. The belonging to the different groups of farmers had a statistical influence on milk quantity and density, according to the feed availability. As well the season had an influence on all the quality and quantity parameters. The time and season of delivery affected significantly the milk quality, instead no influence was attributed to the microbial contamination. The results of this survey showed an adequate qualitative level of the local milk production, which may be improved with a higher feeding system and with a better organisation of the delivery
Signals of Supersymmetric Flavour Models in B Physics
If the mechanism of Supersymmetry breaking is not flavour blind, some flavour
symmetry is likely to be needed to prevent excessive flavour changing neutral
current effects. We discuss two flavour models (based respectively on a U(2)
and on a SU(3) horizontal symmetry) providing a good fit to fermion masses and
mixings and particularly constraining the supersymmetry soft breaking terms. We
show that, while reproducing successfully the Standard Model fit of the
unitarity triangle, it is possible to obtain sizable deviations from the
Standard Model predictions for three very clean B-physics observables: the time
dependent CP asymmetries in and in
and the mass difference. Our analysis exhibits with two
explicit realizations that in supersymmetric theories with a new flavour
structure in addition to the Yukawa matrices there exist concrete
potentialities for revealing supersymmetry indirectly in theoretically clean
-physics observables.Comment: 18 pages, 7 figures, 3 of which in colo
Neutralino Decays in the Complex MSSM at One-Loop: a Comparison of On-Shell Renormalization Schemes
We evaluate two-body decay modes of neutralinos in the Minimal Supersymmetric
Standard Model with complex parameters (cMSSM). Assuming heavy scalar quarks we
take into account all two-body decay channels involving charginos, neutralinos,
(scalar) leptons, Higgs bosons and Standard Model gauge bosons. The evaluation
of the decay widths is based on a full one-loop calculation including hard and
soft QED radiation. Of particular phenomenological interest are decays
involving the Lightest Supersymmetric Particle (LSP), i.e. the lightest
neutralino, or a neutral or charged Higgs boson. For the chargino/neutralino
sector we employ two different renormalization schemes, which differ in the
treatment of the complex phases. In the numerical analysis we concentrate on
the decay of the heaviest neutralino and show the results in the two different
schemes. The higher-order corrections of the heaviest neutralino decay widths
involving the LSP can easily reach a level of about 10-15%, while the
corrections to the decays to Higgs bosons are up to 20-30%, translating into
corrections of similar size in the respective branching ratios. The difference
between the two schemes, indicating the size of unknown two-loop corrections,
is less than order(0.1%). These corrections are important for the correct
interpretation of LSP and Higgs production at the LHC and at a future linear
e+e- collider. The results will be implemented into the Fortran code FeynHiggs.Comment: 49 pages, 27 figures, typos corrected. arXiv admin note: substantial
text overlap with arXiv:1112.0760, arXiv:1111.7289, arXiv:1204.400
Effects of Lepton Flavour Violation on Chargino Production at the Linear Collider
We study the effects of lepton flavour violation (LFV) on the production
processes e+e- --> \chi+_i \chi-_j at a linear collider with longitudinal e+
and e- beam polarizations. In the case of LFV the sneutrino mass eigenstates
have no definite flavour, therefore, in the t-channel more than one sneutrino
mass eigenstate can contribute to the chargino production cross sections. Our
framework is the Minimal Supersymmetric Standard Model (MSSM) including LFV
terms. We show that in spite of the restrictions on the LFV parameters due to
the current limits on rare lepton decays, the cross section \sigma(e+e- -->
\chi+_1 \chi-_1) can change by a factor of 2 or more when varying the LFV
mixing angles. We point out that even if the present bound on BR(tau- --> e-
gamma) improves by a factor of thousand the influence of LFV on the chargino
production cross section can be significant. These results could have an
important impact on the strategies for determining the underlying model
parameters at the linear collider.Comment: 11pp; final version for JHE
Constraints on Natural MNS Parameters from |U_e3|
The MNS matrix structure emerging as a result of recent neutrino measurements
strongly suggests two large mixing angles (solar and atmospheric) and one small
angle (|U_e3| << 1). Especially when combined with the neutrino mass hierarchy,
these values turn out to impose rather stringent constraints on possible flavor
models connecting the three active fermion generations. Specifically, we show
that an extremely small value of |U_e3| would require fine tuning of Majorana
mass matrix parameters, particularly in the context of seesaw models.Comment: 21 pages, ReVTeX, 2 .eps figure files, updated references and
acknowledgment
Minimal Flavour Violation with hierarchical squark masses
In a supersymmetric model with hierarchical squark masses we analyze a
pattern of flavour symmetry breaking centered on the special role of the top
Yukawa coupling and, by extension, of the full Yukawa couplings for the up-type
quarks. For sufficiently heavy squarks of the first and second generation this
leads to effective Minimal Flavour Violation of the Flavour Changing Neutral
Current amplitudes. For this to happen we determine the bounds on the masses of
the heavy squarks with QCD corrections taken into account, properly including
previously neglected effects. We believe that the view presented in this paper
altogether strengthens the case for hierarchical sfermions.Comment: 13 pages, 1 figure. v2: an equation correcte
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