10,159 research outputs found
Relativistic Corrections to the Exclusive Decays of C-even Bottomonia into S-wave Charmonium Pairs
Within the nonrelativistic quantum chromodynamics (NRQCD) factorization
formalism, we compute the relativistic corrections to the exclusive decays of
bottomonia with even charge conjugation parity into -wave charmonium pairs
at leading order in the strong coupling constant. Relativistic corrections are
resummed for a class of color-singlet contributions to all orders in the
charm-quark velocity in the charmonium rest frame. Almost every process
that we consider in this work has negative relativistic corrections ranging
from -20 to -35,%. Among the various processes, the relativistic corrections of
the next-to-leading order in to the decay rate for with or 2 are very large. In every case, the
resummation of the relativistic corrections enhances the rate in comparison
with the next-to-leading-order results. We compare our results with available
predictions based on the NRQCD factorization formalism. The NRQCD predictions
are significantly smaller than those based on the light-cone formalism by an or
two orders of magnitudes.Comment: 20 pages, 1 figure. Typos corrected, published versio
Neutron star properties in density-dependent relativistic Hartree-Fock theory
With the equations of state provided by the newly developed density dependent
relativistic Hartree-Fock (DDRHF) theory for hadronic matter, the properties of
the static and -equilibrium neutron stars without hyperons are studied
for the first time, and compared to the predictions of the relativistic mean
field (RMF) models and recent observational data. The influences of Fock terms
on properties of asymmetric nuclear matter at high densities are discussed in
details. Because of the significant contributions from the - and
-exchange terms to the symmetry energy, large proton fractions in
neutron stars are predicted by the DDRHF calculations, which strongly affect
the cooling process of the star. The critical mass about 1.45 , close
to the limit 1.5 determined by the modern soft X-ray data analysis,
is obtained by DDRHF with the effective interactions PKO2 and PKO3 for the
occurrence of direct Urca process in neutron stars. The maximum masses of
neutron stars given by the DDRHF calculations lie between 2.45 M and
2.49 M, which are in reasonable agreement with high pulsar mass from PSR B1516+02B. It is also found that the mass-radius
relations of neutron stars determined by DDRHF are consistent with the
observational data from thermal radiation measurement in the isolated neutron
star RX J1856, QPOs frequency limits in LMXBs 4U 0614+09 and 4U 1636-536, and
redshift determined in LMXBs EXO 0748-676.Comment: 28 pages, 11 figure
A Millennial Talks Back: Practical Theology as a potential strategy for engaging Australian Millennials in churches?
Modified Bennett-Brassard 1984 Quantum Key Distribution With Two-way Classical Communications
The quantum key distribution protocol without public announcement of bases is
equipped with a two-way classical communication symmetric entanglement
purification protocol. This modified key distribution protocol is
unconditionally secure and has a higher tolerable error rate of 20%, which is
higher than previous scheme without public announcement of bases.Comment: 5 pages. To appear in Physical Review
Umklapp scattering at reconstructed quantum-Hall edges
We study the low-lying excitations of a quantum-Hall sample that has
undergone edge reconstruction such that there exist three branches of chiral
edge excitations. Among the interaction processes that involve electrons close
to the three Fermi points is a new type of Umklapp-scattering process which has
not been discussed before. Using bosonization and a refermionization technique,
we obtain exact results for electronic correlation functions and discuss the
effect Umklapp scattering has on the Luttinger-liquid properties of
quantum-Hall edges.Comment: 4 pages, 1 figure, uses elsart.cls and phbauth.cls (both are
included), contribution to EP2DS-13, to be published in Physica
Equivalent Circuit Modeling of the Dielectric Loaded Microwave Biosensor
This article describes the modeling of biological tissues at microwave frequency using equivalent lumped elements. A microwave biosensor based on microstrip ring resonator (MRR), that has been utilized previously for meat quality evaluation is used for this purpose. For the first time, the ring-resonator loaded with the lossy and high permittivity dielectric material, such as; biological tissue, in a partial overlay configuration is analyzed. The equivalent circuit modeling of the structure is then performed to identify the effect of overlay thickness on the resonance frequency. Finally, the relationship of an overlay thickness with the corresponding RC values of the meat equivalent circuit is established. Simulated, calculated and measured results are then compared for validation. Results are well agreed while the observed discrepancy is in acceptable limit
Health impacts of traffic related air pollution
Ambient air pollution can be a serious cause of concern for any community. Anthropogenic ambient air pollutants can emanate from industries, traffic, geological sources and domestic heating and cooking. However, studies have shown that traffic related air pollution can have far more detrimental health effects than non-combustion sources. These adverse health effects are most profound in sensitive populations like the elderly and young children. The World Health Organization (WHO) attributes more than 300 million deaths every year to ambient air pollution. The WHO’s Air Quality Guidelines (AQG) and the United States Environment Protection Agency’s (USEPA) National Ambient Air Quality Standards (NAAQS) provide specific ambient air quality standards for several air pollutants. This review paper describes some of the criteria air pollutants (as designated by USEPA) like particulate matter, nitrogen dioxide, and carbon monoxide. Short and long term exposures to these pollutants can lead to cardiovascular, respiratory morbidity and premature death in some cases. In the elderly population, exposure to particulate matter has shown an increase in cases of atherosclerosis, irregular heartbeats, emphysema and onset of myocardial infarction. Young children are particularly vulnerable to damaging effects of traffic air pollutants. Children’s lungs are in the process of development and their airway exposure per unit time is more than adults. Also, their defense mechanisms are evolving, thereby, raising their susceptibility to air pollution. In young asthmatic children, exposure to high levels of particulate matter has led to the exacerbation of their asthma. High levels of nitrogen dioxide have shown a decrement in the lung function of young children. This leads to increased rates of school absenteeism, greater use of asthma medications, emergency room visits and hospital admissions. Elucidating the various health effects of traffic pollutants on these sensitive populations is another focal point of this paper
Universality of Uhrig dynamical decoupling for suppressing qubit pure dephasing and relaxation
The optimal -pulse dynamical decoupling discovered by Uhrig for a
spin-boson mmodel [Phys. Rev. Lett, {\bf 98}, 100504 (2007)] is proved to be
universal in suppressing to the pure dephasing or the longitudinal
relaxation of a qubit (or spin-1/2) coupled to a generic bath in a short-time
evolution of duration . It is also found that for the purpose of suppressing
the longitudinal relaxation, an ideal Uhrig -pulse sequence can be
generalized to a sequence consisting of the ideal one superimposed with
finite-duration pulses satisfying certain symmetry requirements.Comment: 4 pages, 1 figure
Leading Chiral Corrections to the Nucleon Generalized Parton Distributions
Using heavy baryon chiral perturbation theory we study the leading chiral
corrections to the complete set of nucleon generalized parton distributions
(GPDs). We compute the leading quark mass and momentum transfer dependence of
the moments of nucleon GPDs through the nucleon off-forward twist-2 matrix
elements. These results are then applied to get insight on the GPDs and their
impact parameter space distributions.Comment: 26 pages, 2 figures; minor revisio
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