12,650 research outputs found
Dispelling the Anthropic Principle from the Dimensionality Arguments
It is shown that in d=11 supergravity, under a very reasonable ansatz, the
nearly flat spacetime in which we are living must be 4-dimensional without
appealing to the Anthropic Principle. Can we dispel the Anthropic Principle
completely from cosmology?Comment: 7 pages, Essa
B ->\eta_c K(\eta_c^\prime K) decays in QCD factorization
We study the exclusive decays of meson into pseudoscalar charmonium
states and within the QCD factorization approach and
find that the nonfactorizable corrections to naive factorization are infrared
safe at leading-twist order. The spectator interactions arising from the kaon
twist-3 effects are formally power-suppressed but chirally and logarithmically
enhanced. The theoretical decay rates are too small to accommodate the
experimental data. On the other hand, we compare the theoretical calculations
for , and , and find that the
predicted relative decay rates of these four states are approximately
compatible with experimental data.Comment: 8 pages, LaTex, 1 figure, one footnote and two references adde
The and decays with the fourth generation
If the fourth generation fermions exist, the new quarks could influence the
branching ratios of the decays of and . We
obtain two solutions of the fourth generation CKM factor
from the decay of . We use these
two solutions to calculate the new contributions of the fourth generation quark
to Wilson coefficients of the decay of . The branching ratio
and the forward-backward asymmetry of the decay of in the two
cases are calculated. Our results are quite different from that of SM in one
case, almost same in another case. If Nature chooses the formmer, the meson
decays could provide a possible test of the forth generation existence.Comment: 10 pages, 5 figure
Enhancing Autonomy in VTOL Aircraft Based on Symbolic Computation Algorithms
Research into the autonomy of small Unmanned Aerial Vehicles (UAVs), and especially on Vertical Take Off and Landing (VTOL) systems has intensified significantly in recent years. This paper develops a generic model of a VTOL UAV in symbolic form. The novelty of this work stems from the designed Model Predictive Control (MPC) algorithm based on this symbolic model. The MPC algorithm is compared with a state-of-the-art Linear Quadratic Regulator algorithm in attitude rate acquisition and its more accurate performance and robustness to noise is demonstrated. Results for the controllers designed for each of the aircraft’s angular rates are presented in response to input disturbances
Electronic Structure of KFeSe from First Principles Calculations
Electronic structure and magnetic properties for iron-selenide KFeSe
are studied by first-principles calculations. The ground state is stripe-like
antiferromagnetic with calculated 2.26 magnetic moment on Fe atoms; and
the , coupling strengths are calculated to be 0.038 eV and 0.029 eV.
The states around are dominated by the Fe-3d orbitals which hybridize
noticeably to the Se-4p orbitals. While the band structure of KFeSe is
similar to a heavily electron-doped BaFeAs or FeSe system, the Fermi
surface of KFeSe is much closer to \fs11 system since the electron
sheets around is symmetric with respect to - exchange. These
features, as well as the absence of Fermi surface nesting, suggest that the
parental KFeSe could be regarded as an electron over-doped 11 system
with possible local moment magnetism.Comment: accepted by Chinese Physics Letter, to appear as Chinese Physics
Letter, Vol 28, page 057402 (2011
On Gravitational anomaly and Hawking radiation near weakly isolated horizon
Based on the idea of the work by Wilczek and his collaborators, we consider
the gravitational anomaly near weekly isolated horizon. We find that there
exists a universal choice of tortoise coordinate for any weakly isolated
horizon. Under this coordinate, the leading behavior of a quite arbitrary
scalar field near horizon is a 2-dimensional chiral scalar field. This means we
can extend the idea of Wilczek and his collaborators to more general cases and
show the relation between gravitational anomaly and Hawking radiation is a
universal property of black hole horizon.Comment: 14 page
A High-Density SNP and SSR Consensus Map Reveals Segregation Distortion Regions in Wheat
Citation: Li, C. L., Bai, G. H., Chao, S. M., & Wang, Z. H. (2015). A High-Density SNP and SSR Consensus Map Reveals Segregation Distortion Regions in Wheat. Biomed Research International, 10. doi:10.1155/2015/830618Segregation distortion is a widespread phenomenon in plant and animal genomes and significantly affects linkage map construction and identification of quantitative trait loci (QTLs). To study segregation distortion in wheat, a high-density consensus map was constructed using single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers by merging two genetic maps developed from two recombinant-inbred line (RIL) populations, Ning7840 x Clark and Heyne x Lakin. Chromosome regions with obvious segregation distortion were identified in the map. A total of 3541 SNPs and 145 SSRs were mapped, and the map covered 3258.7 cM in genetic distance with an average interval of 0.88 cM. The number of markers that showed distorted segregation was 490 (18.5%) in the Ning7840 x Clark population and 225 (10.4%) in the Heyne x Lakin population. Most of the distorted markers (630) were mapped in the consensus map, which accounted for 17.1% of mapped markers. The majority of the distorted markers clustered in the segregation distortion regions (SDRs) on chromosomes 1B, 2A, 2B, 3A, 3B, 4B, 5A, 5B, 5D, 6B, 7A, and 7D. All of the markers in a given SDR skewed toward one of the parents, suggesting that gametophytic competition during zygote formation was most likely one of the causes for segregation distortion in the populations
Multiparty simultaneous quantum identity authentication based on entanglement swapping
We present a multiparty simultaneous quantum identity authentication protocol
based on entanglement swapping. In our protocol, the multi-user can be
authenticated by a trusted third party simultaneously
Decays of and into vector and pseudoscalar meson and the pseudoscalar glueball- mixing
We introduce a parametrization scheme for where
the effects of SU(3) flavor symmetry breaking and doubly OZI-rule violation
(DOZI) can be parametrized by certain parameters with explicit physical
interpretations. This scheme can be used to clarify the glueball-
mixing within the pseudoscalar mesons. We also include the contributions from
the electromagnetic (EM) decays of and via
. Via study of the isospin violated
channels, such as , ,
and , reasonable constraints on the EM decay
contributions are obtained. With the up-to-date experimental data for
, and , etc, we arrive at a consistent description of the mentioned
processes with a minimal set of parameters. As a consequence, we find that
there exists an overall suppression of the form factors,
which sheds some light on the long-standing " puzzle". By determining
the glueball components inside the pseudoscalar and in
three different glueball- mixing schemes, we deduce that the lowest
pseudoscalar glueball, if exists, has rather small component, and it
makes the a preferable candidate for glueball.Comment: Revised version to appear on J. Phys. G; An error in the code was
corrected. There's slight change to the numerical results, while the
conclusion is intac
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