579 research outputs found
Unambiguous Tracking Method Based on Combined Correlation Functions for sine/cosine-BOC CBOC and AltBOC Modulated Signals
Unambiguous tracking for Binary Offset Carrier (BOC) modulated signals is an important requirement of modern Global Navigation Satellite System (GNSS) receivers. An unambiguous tracking method based on combined correlation functions for even/odd order sine/cosine-BOC, Composite BOC(CBOC) and Alternate BOC(AltBOC) modulated signals is proposed. Firstly, a unitary mathematical formulation for all kinds of BOC modulations is introduced. Then an unambiguous tracking method is proposed based on the formulation and the idea of pseudo correlation function (PCF) method. Finally, the tracking loop based on the proposed method is designed. Simulation results indicate that the proposed method can remove side peaks while retaining the sharp main peak for all kinds of BOC modulations. The tracking performance for AltBOC is examined and the results show that the proposed method has better performance in thermal noise and long-delay multipath mitigation than the traditional unambiguous tracking methods
Nonfactorizable decay and QCD factorization
We study the unexpectedly large rate for the factorization-forbidden decay
within the QCD factorization approach. We use a non-zero
gluon mass to regularize the infrared divergences in vertex corrections. The
end-point singularities arising from spectator corrections are regularized and
carefully estimated by the off-shellness of quarks. We find that the
contributions arising from the vertex and leading-twist spectator corrections
are numerically small, and the twist-3 spectator contribution with chiral
enhancement and linear end-point singularity becomes dominant. With reasonable
choices for the parameters, the branching ratio for decay is
estimated to be in the range , which is compatible with
the Belle and BaBar data.Comment: Appendix added; it is emphasized that in the dominant twist-3
spectator corrections the end-point singularity contributions may be
estimated by the off-shellness of the charm quark (by the binding energy in
charmonium) and the gluon (by the transverse momentum of the light quark in
the kaon
A directed mutation operator for real coded genetic algorithms
Copyright @ Springer-Verlag Berlin Heidelberg 2010.Developing directed mutation methods has been an interesting research topic to improve the performance of genetic algorithms (GAs) for function optimization. This paper introduces a directed mutation (DM) operator for GAs to explore promising areas in the search space. In this DM method, the statistics information regarding the fitness and distribution of individuals over intervals of each dimension is calculated according to the current population and is used to guide the mutation of an individual toward the neighboring interval that has the best statistics result in each dimension. Experiments are carried out to compare the proposed DM technique with an existing directed variation on a set of benchmark test problems. The experimental results show that the proposed DM operator achieves a better performance than the directed variation on most test problems
The signal of in nucleon-antinucleon scattering
We study the production of at a nucleon-antinucleon scattering
experiment. Considering the PANDA experiment to be an ideal platform to explore
the production of the charmonium and charmonim-like states, we suggest the
forthcoming PANDA experiment to pay attention to the production of
.Comment: 6 pages, 15 figures. Published version in EPJ
Natural Dark Matter from an Unnatural Higgs Boson and New Colored Particles at the TeV Scale
The thermal relic abundance of Dark Matter motivates the existence of new
electroweak scale particles, independent of naturalness considerations.
However, most unnatural Dark Matter models do not ensure the presence of new
particles charged under SU(3)_C, resulting in challenging LHC phenomenology.
Here, we present a class of models with scalar electroweak doublet Dark Matter
that require a host of colored particles at the TeV scale. In these models, the
Higgs boson is apparently fine-tuned, but the Dark Matter doublet is kept light
without any additional fine-tuning.Comment: 1+22 pages, 5 figures. Added references. Minor clarification
corrections to polarized top decay into a charged Higgs
We calculate the radiative corrections to polarized top quark
decay into a charged Higgs boson and a massive bottom quark in two variants of
the two-Higgs-doublet model. The radiative corrections to the polarization
asymmetry of the decay may become as large as . We provide analytical
formulae for the unpolarized and polarized rates for and for . For our closed-form expressions for the unpolarized and
polarized rates become rather compact.Comment: 24 pages, 5 figures in the text, content modified, comments added,
appendices added, references updated, replaced with published versio
Z-boson as "the standard candle" for high precision W-boson physics at LHC
In this paper we propose a strategy for measuring the inclusive W-boson
production processes at LHC. This strategy exploits simultaneously the unique
flexibility of the LHC collider in running variable beam particle species at
variable beam energies, and the configuration flexibility of the LHC detectors.
We propose their concrete settings for a precision measurement of the Standard
Model parameters. These dedicated settings optimise the use of the Z boson and
Drell-Yan pair production processes as ``the standard reference candles''. The
presented strategy allows to factorise and to directly measure those of the QCD
effects which affect differently the W and Z production processes. It reduces
to a level of 10^{-4} the impact of uncertainties in the partonic distribution
functions (PDFs) and in the transverse momentum of the quarks on the
measurement precision. Last but not the least, it reduces by a factor of 10 an
impact of systematic measurement errors, such as the energy scale and the
measurement resolution, on the W-boson production observables.Comment: 20 pages, 4 figure
Rare Semileptonic Decays of Heavy Mesons with Flavor SU(3) Symmetry
In this paper, we calculate the decay rates of , , , and
semileptonic decay processes, in which only the light
quarks decay, while the heavy flavors remain unchanged. The branching ratios of
these decay processes are calculated with the flavor SU(3) symmetry. The
uncertainties are estimated by considering the SU(3) breaking effect. We find
that the decay rates are very tiny in the framework of the Standard Model. We
also estimate the sensitivities of the measurements of these rare decays at the
future experiments, such as BES-III, super- and LHC-.Comment: 4 pages and 1 figure, accepted by European Physical Journal
Asymmetry Parameter of the by Analyzing the Transition Form Factors within QCD
Separating the mixture of the and states, the
transition form factors are calculated in
the three-point QCD sum rules approach. The longitudinal, transverse and total
decay widths as well as the asymmetry parameter, characterizing the
polarization of the axial and the branching ratio for these
decays are evaluated.Comment: 25 pages, 3 figures, 3 table
A new type of CP symmetry, family replication and fermion mass hierarchies
We study a two-Higgs-doublet model with four generalised CP symmetries in the
scalar sector. Electroweak symmetry breaking leads automatically to spontaneous
breaking of two of them. We require that these four CP symmetries can be
extended from the scalar sector to the full Lagrangian and call this
requirement the principle of maximal CP invariance. The Yukawa interactions of
the fermions are severely restricted by this requirement. In particular, a
single fermion family cannot be coupled to the Higgs fields. For two fermion
families, however, this is possible. Enforcing the absence of flavour-changing
neutral currents, we find degenerate masses in both families or one family
massless and one massive. In the latter case the Lagrangian is highly
symmetric, with the mass hierarchy being generated by electroweak symmetry
breaking. Adding a third family uncoupled to the Higgs fields and thus keeping
it massless we get a model which gives a rough approximation of some features
of the fermions observed in Nature. We discuss a number of predictions of the
model which may be checked in future experiments at the LHC.Comment: 24 pages. Version published in EPJC. Minor changes as suggested by
the refere
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