1,869 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
Design of Energy-Efficient Artificial Noise for Physical Layer Security in Visible Light Communications
This paper studies the design of energy-efficient artificial noise (AN)
schemes in the context of physical layer security in visible light
communications (VLC). Two different transmission schemes termed
and
are examined and
compared in terms of secrecy energy efficiency (SEE). In the former, the
closest LED luminaire to the legitimate user (Bob) is the information-bearing
signal's transmitter. At the same time, the rest of the luminaries act as
jammers transmitting AN to degrade the channels of eavesdroppers (Eves). In the
latter, the information-bearing signal and AN are combined and transmitted by
all luminaries. When Eves' CSI is unknown, an indirect design to improve the
SEE is formulated by maximizing Bob's channel's energy efficiency. A
low-complexity design based on the zero-forcing criterion is also proposed. In
the case of known Eves' CSI, we study the design that maximizes the minimum SEE
among those corresponding to all eavesdroppers. At their respective optimal
SEEs, simulation results reveal that when Eves' CSI is unknown, the selective
AN-aided SISO transmission can archive twice better SEE as the AN-aided MISO
does. In contrast, when Eves' CSI is known, the AN-aided MISO outperforms by
30%
Irreducible representations of Upq[gl(2/2)]
The two-parametric quantum superalgebra and its
representations are considered. All finite-dimensional irreducible
representations of this quantum superalgebra can be constructed and classified
into typical and nontypical ones according to a proposition proved in the
present paper. This proposition is a nontrivial deformation from the one for
the classical superalgebra gl(2/2), unlike the case of one-parametric
deformations.Comment: Latex, 8 pages. A reference added in v.
New determination of structure parameters in strong field tunneling ionization theory of molecules
In the strong field molecular tunneling ionization theory of Tong et al.
[Phys. Rev. A 66, 033402 (2002)], the ionization rate depends on the asymptotic
wavefunction of the molecular orbital from which the electron is removed. The
orbital wavefunctions obtained from standard quantum chemistry packages in
general are not good enough in the asymptotic region. Here we construct a
one-electron model potential for several linear molecules using density
functional theory (DFT). We show that the asymptotic wavefunction can be
improved with an iteration method and after one iteration accurate asymptotic
wavefunctions and structure parameters are determined. With the new parameters
we examine the alignment-dependent tunneling ionization probabilities for
several molecules and compare with other calculations and with recent
measurements, including ionization from inner molecular orbitals
New onset diabetes after transplantation (NODAT): an overview
Although renal transplantation ameliorates cardiovascular risk factors by restoring renal function, it introduces new cardiovascular risks including impaired glucose tolerance or diabetes mellitus, hypertension, and dyslipidemia that are derived, in part, from immunosuppressive medications such as calcineurin inhibitors, corticosteroids, or mammalian target of rapamycin inhibitors. New onset diabetes mellitus after transplantation (NODAT) is a serious and common complication following solid organ transplantation. NODAT has been reported to occur in 2% to 53% of all solid organ transplants. Kidney transplant recipients who develop NODAT have variably been reported to be at increased risk of fatal and nonfatal cardiovascular events and other adverse outcomes including infection, reduced patient survival, graft rejection, and accelerated graft loss compared with those who do not develop diabetes. Identification of high-risk patients and implementation of measures to reduce the development of NODAT may improve long-term patient and graft outcome. The following article presents an overview of the literature on the current diagnostic criteria for NODAT, its incidence after solid organ transplantation, suggested risk factors and potential pathogenic mechanisms. The impact of NODAT on patient and allograft outcomes and suggested guidelines for early identification and management of NODAT will also be discussed
Minimal Scalar Sector of 3-3-1 Models without Exotic Electric Charges
We study the minimal set of Higgs scalars, for models based on the local
gauge group which do not contain
particles with exotic electric charges. We show that only two Higgs
triplets are needed in order to properly break the symmetry. The exact
tree-level scalar mass matrices resulting from symmetry breaking are calculated
at the minimum of the most general scalar potential, and the gauge bosons are
obtained, together with their couplings to the physical scalar fields. We show
how the scalar sector introduced is enough to produce masses for fermions in a
particular model which is an subgroup. By using experimental results we
constrain the scale of new physics to be above 1.3 TeV.Comment: LaTeX, 22 pages, 1 figure include
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