54,585 research outputs found
Combined large-N_c and heavy-quark operator analysis for the chiral Lagrangian with charmed baryons
The chiral Lagrangian with charmed baryons of spin and
is analyzed. We consider all counter terms that are relevant at
next-to-next-to-next-to-leading order (NLO) in a chiral extrapolation of
the charmed baryon masses. At NLO we find 16 low-energy parameters. There
are 3 mass parameters for the anti-triplet and the two sextet baryons, 6
parameters describing the meson-baryon vertices and 7 symmetry breaking
parameters. The heavy-quark spin symmetry predicts four sum rules for the
meson-baryon vertices and degenerate masses for the two baryon sextet fields.
Here a large- operator analysis at NLO suggests the relevance of one
further spin-symmetry breaking parameter. Going from NLO to NLO adds 17
chiral symmetry breaking parameters and 24 symmetry preserving parameters. For
the leading symmetry conserving two-body counter terms involving two baryon
fields and two Goldstone boson fields we find 36 terms. While the heavy-quark
spin symmetry leads to sum rules, an expansion in at
next-to-leading order (NLO) generates parameter relations. A
combined expansion leaves 3 unknown parameters only. For the symmetry breaking
counter terms we find 17 terms, for which there are sum rules from the
heavy-quark spin symmetry and sum rules from a expansion at
NLO.Comment: 34 pages - one table - corrections applie
Growth mechanism of nanostructured superparamagnetic rods obtained by electrostatic co-assembly
We report on the growth of nanostructured rods fabricated by electrostatic
co-assembly between iron oxide nanoparticles and polymers. The nanoparticles
put under scrutiny, {\gamma}-Fe2O3 or maghemite, have diameter of 6.7 nm and
8.3 nm and narrow polydispersity. The co-assembly is driven by i) the
electrostatic interactions between the polymers and the particles, and by ii)
the presence of an externally applied magnetic field. The rods are
characterized by large anisotropy factors, with diameter 200 nm and length
comprised between 1 and 100 {\mu}m. In the present work, we provide for the
first time the morphology diagram for the rods as a function of ionic strength
and concentration. We show the existence of a critical nanoparticle
concentration and of a critical ionic strength beyond which the rods do not
form. In the intermediate regimes, only tortuous and branched aggregates are
detected. At higher concentrations and lower ionic strengths, linear and stiff
rods with superparamagnetic properties are produced. Based on these data, a
mechanism for the rod formation is proposed. The mechanism proceeds in two
steps : the formation and growth of spherical clusters of particles, and the
alignment of the clusters induced by the magnetic dipolar interactions. As far
as the kinetics of these processes is concerned, the clusters growth and their
alignment occur concomitantly, leading to a continuous accretion of particles
or small clusters, and a welding of the rodlike structure.Comment: 15 pages, 10 figures, one tabl
Achievable efficiencies for probabilistically cloning the states
We present an example of quantum computational tasks whose performance is
enhanced if we distribute quantum information using quantum cloning.
Furthermore we give achievable efficiencies for probabilistic cloning the
quantum states used in implemented tasks for which cloning provides some
enhancement in performance.Comment: 9 pages, 8 figure
A magnetized torus for modeling Sgr A* millimeter images and spectra
Context. The supermassive black hole, Sagittarius (Sgr) A*, in the centre of
our Galaxy has the largest angular size in the sky among all astrophysical
black holes. Its shadow, assuming no rotation, spans ~ 50 microarcsec.
Resolving such dimensions has long been out of reach for astronomical
instruments until a new generation of interferometers being operational during
this decade. Of particular interest is the Event Horizon Telescope (EHT) with
resolution ~ 20 microarcsec in the millimeter-wavelength range 0.87 mm - 1.3
mm. Aims. We investigate the ability of the fully general relativistic
Komissarov (2006) analytical magnetized torus model to account for observable
constraints at Sgr A* in the centimeter and millimeter domains. The impact of
the magnetic field geometry on the observables is also studied. Methods. We
calculate ray-traced centimeter- and millimeter-wavelength synchrotron spectra
and images of a magnetized accretion torus surrounding the central black hole
in Sgr A*. We assume stationarity, axial symmetry, constant specific angular
momentum and polytropic equation of state. A hybrid population of thermal and
non-thermal electrons is considered. Results. We show that the torus model is
capable of reproducing spectral constraints in the millimeter domain, and in
particular in the observable domain of the EHT. However, the torus model is not
yet able to fit the centimeter spectrum. 1.3 mm images at high inclinations are
in agreement with observable constraints. Conclusions. The ability of the torus
model to account for observations of Sgr A* in the millimeter domain is
interesting in the perspective of the future EHT. Such an analytical model
allows very fast computations. It will thus be a suitable test bed for
investigating large domains of physical parameters, as well as non-black-hole
compact object candidates and alternative theories of gravity.Comment: Major changes wrt the June 2014 version. Accepted by A&
Probabilistic teleportation of unknown two-particle state via POVM
We propose a scheme for probabilistic teleportation of unknown two-particle
state with partly entangled four-particle state via POVM. In this scheme the
teleportation of unknown two-particle state can be realized with certain
probability by performing two Bell state measurements, a proper POVM and a
unitary transformation.Comment: 5 pages, no figur
Poly(acrylic acid)-coated iron oxide nanoparticles : quantitative evaluation of the coating properties and applications for the removal of a pollutant dye
In this work, 6 to 12 nm iron oxide nanoparticles were synthesized and coated
with poly(acrylic acid) chains of molecular weight 2100 g/mol. Based on a
quantitative evaluation of the dispersions, the bare and coated particles were
thoroughly characterized. The number densities of polymers adsorbed at the
particle surface and of available chargeable groups were found to be 1.9 +/-
0.3 nm-2 and 26 +/- 4 nm-2, respectively. Occurring via a multi-site binding
mechanism, the electrostatic coupling leads to a solid and resilient anchoring
of the chains. To assess the efficacy of the particles for pollutant
remediation, the adsorption isotherm of methylene blue molecules, a model of
pollutant, was determined. The excellent agreement between the predicted and
measured amounts of adsorbed dyes suggests that most carboxylates participate
to the complexation and adsorption mechanisms. An adsorption of 830 mg/g was
obtained. This quantity compares well with the highest values available for
this dye.Comment: 14 pages 5 figures, accepted 06-Dec-2012; Journal of Colloid and
Interface Science (2013
Variational calculations on the hydrogen molecular ion
We present high-precision non-relativistic variational calculations of bound
vibrational-rotational state energies for the and molecular
ions in each of the lowest electronic states of , , and
symmetry. The calculations are carried out including coupling between
and states but without using the Born-Oppenheimer or any
adiabatic approximation. Convergence studies are presented which indicate that
the resulting energies for low-lying levels are accurate to about .
Our procedure accounts naturally for the lambda-doubling of the state.Comment: 23 pp., RevTeX, epsf.sty, 5 figs. Enhanced data in Table II, dropped
3 figs. from previous versio
- …