5,495 research outputs found
Generalized reflection symmetry and leptonic CP violation
We propose a generalized reflection symmetry to constrain the
lepton flavor mixing parameters. We obtain a new correlation between the
atmospheric mixing angle and the "Dirac" CP violation phase
. Only in a specific limit our proposed CP transformation
reduces to standard reflection, for which and
are both maximal. The "Majorana" phases are predicted to lie at
their CP-conserving values with important implications for the neutrinoless
double beta decay rates. We also study the phenomenological implications of our
scheme for present and future neutrino oscillation experiments including T2K,
NOA and DUNE.Comment: 14 pages, 9 figures, latex, Final version to appear in Physics
Letters
Phase-field-crystal modeling of the (2x1)-(1x1) phase-transitions of Si(001) and Ge(001) surfaces
We propose a two-dimensional phase-field-crystal model for the
(21)-(11) phase transitions of Si(001) and Ge(001) surfaces.
The dimerization in the 21 phase is described with a
phase-field-crystal variable which is determined by solving an evolution
equation derived from the free energy. Simulated periodic arrays of
dimerization variable is consistent with scanning-tunnelling-microscopy images
of the two dimerized surfaces. Calculated temperature dependence of the
dimerization parameter indicates that normal dimers and broken ones coexist
between the temperatures describing the charactristic temperature width of the
phase-transition, and , and a first-order phase transition takes
place at a temperature between them. The dimerization over the whole
temperature is determined. These results are in agreement with experiment. This
phase-field-crystal approach is applicable to phase-transitions of other
reconstructed surface phases, especially semiconductor 1 reconstructed
surface phases.Comment: 10 pages with 4 figures include
Warped flavor symmetry predictions for neutrino physics
A realistic five-dimensional warped scenario with all standard model fields
propagating in the bulk is proposed. Mass hierarchies would in principle be
accounted for by judicious choices of the bulk mass parameters, while fermion
mixing angles are restricted by a flavor symmetry broken on the
branes by flavon fields. The latter gives stringent predictions for the
neutrino mixing parameters, and the Dirac CP violation phase, all described in
terms of only two independent parameters at leading order. The scheme also
gives an adequate CKM fit and should be testable within upcoming oscillation
experiments.Comment: 19 pages, 2 figue
Controllable selective exfoliation of high-quality graphene nanosheets and nanodots by ionic liquid assisted grinding
Bulk quantities of graphene nanosheets and nanodots have been selectively
fabricated by mechanical grinding exfoliation of natural graphite in a small
quantity of ionic liquids. The resulting graphene sheets and dots are solvent
free with low levels of naturally absorbed oxygen, inherited from the starting
graphite. The sheets are only two to five layers thick. The graphene nanodots
have diameters in the range of 9-29 nm and heights in the range of 1-16 nm,
which can be controlled by changing the processing time.Comment: * Corresponding authors: [email protected];
[email protected]
Thermal radiation in non-static curved spacetimes: quantum mechanical path integrals and configuration space topology
A quantum mechanical path integral derivation is given of a thermal
propagator in non-static Gui spacetime. The thermal nature of the propagator is
understood in terms of homotopically non-trivial paths in the configuration
space appropriate to tortoise coordinates. The connection to thermal emission
from collapsing black holes is discussed.Comment: 20 pages, major revised version, 9 figures, new titl
Probability density function of bubble size based reagent dosage predictive control for copper roughing flotation
As an effective measurement indicator of bubble stability, bubble size structure is believed to be closely related to flotation performance in copper roughing flotation. Moreover, reagent dosage has a very important influence on bubble size structure. In this paper, a novel reagent dosage predictive control method based on probability density function (PDF) of bubble size is proposed to implement the indices of roughing circuit. Firstly, the froth images captured in the copper roughing are segmented by using a two-pass watershed algorithm. In order to characterize bubble size structure with non-Gaussian feature, an entropy based B-spline estimator is hence investigated to depict the PDF of the bubble size. Since the weights of B-spline are interrelated and related to the reagent dosage, a multi-output least square support vector machine (MLS-SVM) is applied to depict a dynamic relationship between the weights and the reagent dosage. Finally, an entropy based optimization algorithm is proposed to determine reagent dosage in order to implement tracking control for the PDF of the output bubble size. Experimental results can show the effectiveness of the proposed method
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