1,663 research outputs found
The Oblique Corrections from Heavy Scalars in Irreducible Representations
The contributions to , , and from heavy scalars in any irreducible
representation of the electroweak gauge group are
obtained. We find that in the case of a heavy scalar doublet there is a slight
difference between the parameter we have obtained and that in previous
works.Comment: 6 pages, 2 axodraw figures; minor changes, references update
Triaxially deformed relativistic point-coupling model for hypernuclei: a quantitative analysis of hyperon impurity effect on nuclear collective properties
The impurity effect of hyperon on atomic nuclei has received a renewed
interest in nuclear physics since the first experimental observation of
appreciable reduction of transition strength in low-lying states of
hypernucleus Li. Many more data on low-lying states of
hypernuclei will be measured soon for -shell nuclei, providing good
opportunities to study the impurity effect on nuclear low-energy
excitations. We carry out a quantitative analysis of hyperon impurity
effect on the low-lying states of -shell nuclei at the beyond-mean-field
level based on a relativistic point-coupling energy density functional (EDF),
considering that the hyperon is injected into the lowest
positive-parity () and negative-parity () states. We
adopt a triaxially deformed relativistic mean-field (RMF) approach for
hypernuclei and calculate the binding energies of hypernuclei as well
as the potential energy surfaces (PESs) in deformation plane.
We also calculate the PESs for the hypernuclei with good quantum
numbers using a microscopic particle rotor model (PRM) with the same
relativistic EDF. The triaxially deformed RMF approach is further applied in
order to determine the parameters of a five-dimensional collective Hamiltonian
(5DCH) for the collective excitations of triaxially deformed core nuclei.
Taking Mg and Si as examples, we analyse
the impurity effects of and on the low-lying states of
the core nuclei...Comment: 15 pages with 18 figures and 1 table (version to be published in
Physical Review C
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Discussion On Device Structures And Hermetic Encapsulation For SiOx Random Access Memory Operation In Air
An edge-free structure and hermetic encapsulation technique are presented that enable SiOx-based resistive random-access memory (RRAM) operation in air. A controlled etch study indicates that the switching filament is close to the SiOx surface in devices with an exposed SiOx edge. Electrical test of encapsulated, edge-free devices in 1 atmosphere air indicates stable switching characteristics, unlike devices with an edge. This work demonstrates that SiOx RRAM is able to operate in air with proper encapsulation and an edge-free structure. The resistive switching failure mechanism when operating in air is explained by the oxidation of hydrogen-complexed defects in the switching filament. (C) 2014 AIP Publishing LLC.National Science Foundation IIP-1127537Microelectronics Research Cente
Symmetry of Dirac Equation and Corresponding Phenomenology
It has been suggested that the high symmetries in the Schr\"odinger equation
with the Coulomb or harmonic oscillator potentials may remain in the
corresponding relativistic Dirac equation. If the principle is correct, in the
Dirac equation the potential should have a form as
where is for hydrogen atom and for harmonic
oscillator. However, in the case of hydrogen atom, by this combination the
spin-orbit coupling term would not exist and it is inconsistent with the
observational spectra of hydrogen atom, so that the symmetry of SO(4) must
reduce into SU(2). The governing mechanisms QED and QCD which induce potential
are vector-like theories, so at the leading order only vector potential exists.
However, the higher order effects may cause a scalar fraction. In this work, we
show that for QED, the symmetry restoration is very small and some discussions
on the symmetry breaking are made. At the end, we briefly discuss the QCD case
and indicate that the situation for QCD is much more complicated and
interesting.Comment: 15pages, 3 figures, accepted by International Journal of Modern
Physics
Neutrino decay as a possible interpretation to the MiniBooNE observation with unparticle scenario
In a new measurement on neutrino oscillation , the
MiniBooNE Collaboration observes an excess of electron-like events at low
energy and the phenomenon may demand an explanation which obviously is beyond
the oscillation picuture. We propose that heavier neutrino decaying
into a lighter one via the transition process
where denotes any light products, could be a natural mechanism. The
theoretical model we employ here is the unparticle scenario established by
Georgi. We have studied two particular modes \nu_\mu\to \nu_e+\Un and
. Unfortunately, the number coming out from
the computation is too small to explain the observation. Moreover, our results
are consistent with the cosmology constraint on the neutrino lifetime and the
theoretical estimation made by other groups, therefore we can conclude that
even though neutrino decay seems plausible in this case, it indeed cannot be
the source of the peak at lower energy observed by the MiniBooNE collaboration
and there should be other mechanisms responsible for the phenomenon.Comment: 14 pages, conclusions are changed; published version for EPJ
Thermal Unparticles: A New Form of Energy Density in the Universe
Unparticle \U with scaling dimension d_\U has peculiar thermal properties
due to its unique phase space structure. We find that the equation of state
parameter \omega_\U, the ratio of pressure to energy density, is given by
1/(2d_\U +1) providing a new form of energy in our universe. In an expanding
universe, the unparticle energy density \rho_\U(T) evolves dramatically
differently from that for photons. For d_\U >1, even if \rho_\U(T_D) at a
high decoupling temperature is very small, it is possible to have a large
relic density \rho_\U(T^0_\gamma) at present photon temperature ,
large enough to play the role of dark matter. We calculate and
\rho_\U(T^0_\gamma) using photon-unparticle interactions for illustration.Comment: 5 pages; v3, journal version
Restudy on Dark Matter Time-Evolution in the Littlest Higgs model with T-parity
Following previous study, in the Littlest Higgs model (LHM), the heavy photon
is supposed to be a possible dark matter candidate and its relic abundance of
the heavy photon is estimated in terms of the Boltzman-Lee-Weinberg
time-evolution equation. The effects of the T-parity violation is also
considered. Our calculations show that when Higgs mass taken to be 300
GeV and don't consider T-parity violation, only two narrow ranges
GeV and GeV are tolerable with the
current astrophysical observation and if GeV, there must at
least exist another species of heavy particle contributing to the cold dark
matter. As long as the T-parity can be violated, the heavy photon can decay
into regular standard model particles and would affect the dark matter
abundance in the universe, we discuss the constraint on the T-parity violation
parameter based on the present data. Direct detection prospects are also
discussed in some detail.Comment: 13 pages, 11 figures include
Reducing the communication complexity with quantum entanglement
We propose a probabilistic two-party communication complexity scenario with a
prior nonmaximally entangled state, which results in less communication than
that is required with only classical random correlations. A simple all-optical
implementation of this protocol is presented and demonstrates our conclusion.Comment: 4 Pages, 2 Figure
Skin transcriptome profiles associated with coat color in sheep
Background
Previous molecular genetic studies of physiology and pigmentation of sheep skin have focused primarily on a limited number of genes and proteins. To identify additional genes that may play important roles in coat color regulation, Illumina sequencing technology was used to catalog global gene expression profiles in skin of sheep with white versus black coat color. Results
There were 90,006 and 74,533 unigenes assembled from the reads obtained from white and black sheep skin, respectively. Genes encoding for the ribosomal proteins and keratin associated proteins were most highly expressed. A total of 2,235 known genes were differentially expressed in black versus white sheep skin, with 479 genes up-regulated and 1,756 genes down-regulated. A total of 845 novel genes were differentially expressed in black versus white sheep skin, consisting of 107 genes which were up-regulated (including 2 highly expressed genes exclusively expressed in black sheep skin) and 738 genes that were down-regulated. There was also a total of 49 known coat color genes expressed in sheep skin, from which 13 genes showed higher expression in black sheep skin. Many of these up-regulated genes, such as DCT, MATP, TYR and TYRP1, are members of the components of melanosomes and their precursor ontology category. Conclusion
The white and black sheep skin transcriptome profiles obtained provide a valuable resource for future research to understand the network of gene expression controlling skin physiology and melanogenesis in sheep
A possible signature of new physics at BES-III
The recent observations of the purely leptonic decay \Ds \to \mu^+
\nu_{\mu} and at CLEO-c and factory may allow a
possible contribution from a charged Higgs boson. One such measurement of the
decay constant differs from the most precise unquenched lattice QCD
calculation by 4 level. Meanwhile, the measured ratio, {\cal BR}(\Ds
\to \mu^+ \nu_{\mu}) / {\cal BR}(\Dp \to \mu^+ \nu_{\mu}), is larger than
the standard model prediction at 2.0 level. We discuss that the precise
measurement of the ratio {\cal BR}(\Ds \to \mu^+ \nu_{\mu}) / {\cal BR}(\Dp
\to \mu^+ \nu_{\mu}) at BES-III will shed light on the presence of new
intermediate particles by comparing the theoretical predictions, especially,
the predictions of high precise unquenched lattice QCD calculation.Comment: 5 pages, 3 figures, mini-review, accepted by Chinese Physics C (HEP &
NP
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