46,871 research outputs found
Fermion masses in the economical 3-3-1 model
We show that, in frameworks of the economical 3-3-1 model, all fermions get
masses. At the tree level, one up-quark and two down-quarks are massless, but
the one-loop corrections give all quarks the consistent masses. This conclusion
is in contradiction to the previous analysis in which, the third scalar triplet
has been introduced. This result is based on the key properties of the model:
First, there are three quite different scales of vacuum expectation values:
\om \sim {\cal O}(1) \mathrm{TeV}, v \approx 246 \mathrm{GeV} and . Second, there exist two types of Yukawa couplings
with different strengths: the lepton-number conserving couplings 's and the
lepton-number violating ones 's satisfying the condition in which the second
are much smaller than the first ones: .
With the acceptable set of parameters, numerical evaluation shows that in
this model, masses of the exotic quarks also have different scales, namely, the
exotic quark () gains mass GeV, while the
D_\al exotic quarks (q_{D_\al} = -1/3) have masses in the TeV scale:
m_{D_\al} \in 10 \div 80 TeV.Comment: 20 pages, 8 figure
Refinement Type Inference via Horn Constraint Optimization
We propose a novel method for inferring refinement types of higher-order
functional programs. The main advantage of the proposed method is that it can
infer maximally preferred (i.e., Pareto optimal) refinement types with respect
to a user-specified preference order. The flexible optimization of refinement
types enabled by the proposed method paves the way for interesting
applications, such as inferring most-general characterization of inputs for
which a given program satisfies (or violates) a given safety (or termination)
property. Our method reduces such a type optimization problem to a Horn
constraint optimization problem by using a new refinement type system that can
flexibly reason about non-determinism in programs. Our method then solves the
constraint optimization problem by repeatedly improving a current solution
until convergence via template-based invariant generation. We have implemented
a prototype inference system based on our method, and obtained promising
results in preliminary experiments.Comment: 19 page
The Effect of wake Turbulence Intensity on Transition in a Compressor Cascade
Direct numerical simulations of separating flow along a section at midspan of a low-pressure V103 compressor cascade with periodically incoming wakes were performed. By varying the strength of the wake, its influence on both boundary layer separation and bypass transition were examined. Due to the presence of small-scale three-dimensional fluctuations in the wakes, the flow along the pressure surface undergoes bypass transition. Only in the weak-wake case, the boundary layer reaches a nearly-separated state between impinging wakes. In all simulations, the flow along the suction surface was found to separate. In the simulation with the strong wakes, separation is intermittently suppressed as the periodically passing wakes managed to trigger turbulent spots upstream of the location of separation. As these turbulent spots convect downstream, they locally suppress separation. © 2014 Springer Science+Business Media Dordrecht
Cancellation of Infrared Divergences in Hadronic Annihilation Decays of Heavy Quarkonia
In the framework of a newly developed factorization formalism which is based
on NRQCD, explicit cancellations are shown for the infrared divergences that
appeared in the previously calculated hadronic annihilation decay rates of
P-wave and D-wave heavy quarkonia. We extend them to a more general case that
to leading order in and next-to-leading order in , the infrared
divergences in the annihilation amplitudes of color-singlet
pair can be removed by including the contributions of
color-octet operators ,
, ... in NRQCD. We also give the decay widths of
at leading order in .Comment: 8 pages, LaTex(3 figures included), to be publishe
Etude de la qualitĂ© bactĂ©riologique des aliments vendus sur le campus de lâUniversitĂ© dâAbomey Calavi au BĂ©nin
Selon l'Organisation Mondiale de la SantĂ©, deux millions de personnes dans les pays en dĂ©veloppement dĂ©cĂšdent chaque annĂ©e, Ă cause des intoxications alimentaires contractĂ©es en partie dans la restauration de masse. Le double objectif de cette Ă©tude Ă©tait dâanalyser la qualitĂ© bactĂ©riologique des aliments vendus en restauration rapide sur le campus universitaire et de dĂ©terminer la frĂ©quence des bactĂ©ries multi rĂ©sistantes (BMR) isolĂ©es. En six mois; 390 Ă©chantillons dâaliments ont Ă©tĂ© collectĂ©s et analysĂ©s. Escherichia coli, Salmonella, Staphylococcus aureus et Enterococcus ont Ă©tĂ© recherchĂ©es. Les bactĂ©ries ont Ă©tĂ© dĂ©nombrĂ©es puis identifiĂ©es suivant les mĂ©thodes biochimiques classiques. Un antibiogramme a Ă©tĂ© rĂ©alisĂ© sur les souches isolĂ©es. Le sĂ©rotype Escherichia coli O157 et les souches dâEscherichia coli productrices de bĂȘta lactamase Ă spectre Ă©largi (ECBLSE) ont Ă©tĂ© recherchĂ©s. 74% des prĂ©lĂšvements sont contaminĂ©s; 325 souches des bactĂ©ries recherchĂ©es sont isolĂ©es, dont 116 (36%) constituent des BMR parmi lesquelles 44% de ECBLSE, 32% de Staphylococcus aureus rĂ©sistante Ă la mĂ©ticilline et 24% dâEntĂ©rocoque rĂ©sistant Ă la vancomycine. Deux souches de Salmonella enteritidis et 21 souches dâEscherichia coli O157 ont Ă©tĂ© dĂ©tectĂ©es. Il ressort de ces rĂ©sultats que la qualitĂ© bactĂ©riologique des aliments analysĂ©s nâest pas satisfaisante; la proportion de BMR est Ă©levĂ©e, et la transmission aux consommateurs est possible.© 2010 International Formulae Group. All rights reserved.Mots clĂ©s: Toxi-infection alimentaire; BMR, campus universitaire, BĂ©ni
Neutrino masses in the economical 3-3-1 model
We show that, in frameworks of the economical 3-3-1 model, the suitable
pattern of neutrino masses arises from the three quite different sources - the
lepton-number conserving, the spontaneous lepton-number breaking and the
explicit lepton-number violating, widely ranging over the mass scales including
the GUT one: , , \om\sim
O(1) \mathrm{TeV} and . At
the tree-level, the model contains three Dirac neutrinos: one massless, two
large with degenerate masses in the order of the electron mass. At the one-loop
level, the left-handed and right-handed neutrinos obtain Majorana masses
in orders of and degenerate in
, while the Dirac masses get a large reduction down to
scale through a finite mass renormalization. In this model, the contributions
of new physics are strongly signified, the degenerations in the masses and the
last hierarchy between the Majorana and Dirac masses can be completely removed
by heavy particles. All the neutrinos get mass and can fit the data.Comment: 15 pages, 8 figure
decay to two-charm quark jets as a Probe of the Color Octet Mechanism
We calculate the decay rate of bottomonium to two-charm quark jets at the tree level and one-loop level including color-singlet and
color-octet annihilations. We find that the short distance
coefficient of the color-octet piece is much larger than the color-singlet
piece, and that the QCD correction will change the endpoint behavior of the
charm quark jet. The color-singlet piece is strongly affected by the one-loop
QCD correction. In contrast, the QCD correction to the color-octet piece is
weak. Once the experiment can measure the branching ratio and energy
distribution of the two-charm quark jets in the decay, the result
can be used to test the color octet mechanism or give a strong constraint on
the color-octet matrix elements.Comment: Accepted for publication in Phys. Rev. D, Appendices adde
Local spin and charge properties of beta-Ag0.33V2O5 studied by 51V NMR
Local spin and charge properties were studied on beta-Ag0.33V2O5, a
pressure-induced superconductor, at ambient pressure using 51V-NMR and
zero-field-resonance (ZFR) techniques. Three inequivalent Vi sites (i=1, 2, and
3) were identified from 51V-NMR spectra and the principal axes of the
electric-field-gradient (EFG) tensor were determined in a metallic phase and
the following charge-ordering phase. We found from the EFG analysis that the V1
sites are in a similar local environment to the V3 sites. This was also
observed in ZFR spectra as pairs of signals closely located with each other.
These results are well explained by a charge-sharing model where a 3d1 electron
is shared within a rung in both V1-V3 and V2-V2 two-leg ladders.Comment: 12pages, 16figure
Volcanic ash supply to the surface ocean â remote sensing of biological responses and their wider biogeochemical significance
Transient micronutrient enrichment of the surface ocean can enhance phytoplankton growth rates and alter microbial community structure with an ensuing spectrum of biogeochemical feedbacks. Strong phytoplankton responses to micronutrients supplied by volcanic ash have been reported recently. Here we: (i) synthesize findings from these recent studies; (ii) report the results of a new remote sensing study of ash fertilization; and (iii) calculate theoretical bounds of ash-fertilized carbon export. Our synthesis highlights that phytoplankton responses to ash do not always simply mimic that of iron amendment; the exact mechanisms for this are likely biogeochemically important but are not yet well understood. Inherent optical properties of ash-loaded seawater suggest rhyolitic ash biases routine satellite chlorophyll-a estimation upwards by more than an order of magnitude for waters with 0.5 mg chlorophyll-a m-3. For this reason post-ash-deposition chlorophyll-a changes in oligotrophic waters detected via standard Case 1 (open ocean) algorithms should be interpreted with caution. Remote sensing analysis of historic events with a bias less than a factor of 2 provided limited stand-alone evidence for ash-fertilization. Confounding factors were poor coverage, incoherent ash dispersal, and ambiguity ascribing biomass changes to ash supply over other potential drivers. Using current estimates of iron release and carbon export efficiencies, uncertainty bounds of ash-fertilized carbon export for 3 events are presented. Patagonian iron supply to the Southern Ocean from volcanic eruptions is less than that of windblown dust on thousand year timescales but can dominate supply at shorter timescales. Reducing uncertainties in remote sensing of phytoplankton response and nutrient release from ash are avenues for enabling assessment of the oceanic response to large-scale transient nutrient enrichment
On spherical twisted conjugacy classes
Let G be a simple algebraic group over an algebraically closed field of good
odd characteristic, and let theta be an automorphism of G arising from an
involution of its Dynkin diagram. We show that the spherical theta-twisted
conjugacy classes are precisely those intersecting only Bruhat cells
corresponding to twisted involutions in the Weyl group. We show how the
analogue of this statement fails in the triality case. We generalize to good
odd characteristic J-H. Lu's dimension formula for spherical twisted conjugacy
classes.Comment: proof of Lemma 6.4 polished. The journal version is available at
http://www.springerlink.com/content/k573l88256753640
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