1,561,029 research outputs found
Imaging and quantum efficiency measurement of chromium emitters in diamond
We present direct imaging of the emission pattern of individual
chromium-based single photon emitters in diamond and measure their quantum
efficiency. By imaging the excited state transition dipole intensity
distribution in the back focal plane of high numerical aperture objective, we
determined that the emission dipole is oriented nearly orthogonal to the
diamond-air interface. Employing ion implantation techniques, the emitters were
engineered with various proximities from the diamond-air interface. By
comparing the decay rates from the single chromium emitters at different depths
in the diamond crystal, an average quantum efficiency of 28% was measured.Comment: 11 pages and 4 figure
Comment on "Mass and K Lambda coupling of N*(1535)"
It is argued in [1] that when the strong coupling to the K Lambda channel is
considered, Breit-Wigner mass of the lightest orbital excitation of the nucleon
N(1535) shifts to a lower value. The new value turned out to be smaller than
the mass of the lightest radial excitation N(1440), which effectively solved
the long-standing problem of conventional constituent quark models. In this
Comment we show that it is not the Breit-Wigner mass of N(1535) that is
decreased, but its bare mass.
[1] B. C. Liu and B. S. Zou, Phys. Rev. Lett. 96, 042002 (2006).Comment: 3 pages, comment on "Mass and K Lambda coupling of N*(1535)", B. C.
Liu and B. S. Zou, Phys. Rev. Lett. 96, 042002 (2006
Strangeness magnetic form factor of the proton in the extended chiral quark model
Background: Unravelling the role played by nonvalence flavors in baryons is
crucial in deepening our comprehension of QCD. Strange quark, a component of
the higher Fock states in baryons, is an appropriate tool to investigate
nonperturbative mechanisms generated by the pure sea quark.
Purpose: Study the magnitude and the sign of the strangeness magnetic moment
and the magnetic form factor () of the proton.
Methods: Within an extended chiral constituent quark model, we investigate
contributions from all possible five-quark components to and in the four-vector momentum range (GeV/c). Probability
of the strangeness component in the proton wave function is calculated
employing the model.
Results: Predictions are obtained without any adjustable parameters.
Observables and are found to be small and negative,
consistent with the lattice-QCD findings as well as with the latest data
released by the PVA4 and HAPPEX Collaborations.
Conclusions: Due to sizeable cancelations among different configurations
contributing to the strangeness magnetic moment of the proton, it is
indispensable to (i) take into account all relevant five-quark components and
include both diagonal and non-diagonal terms, (ii) handle with care the
oscillator harmonic parameter and the component
probability.Comment: References added, typos corrected, accepted for publication by Phys.
Rev.
Competing Glauber and Kawasaki Dynamics
Using a quantum formulation of the master equation we study a kinetic Ising
model with competing stochastic processes: the Glauber dynamics with
probability and the Kawasaki dynamics with probability . Introducing
explicitely the coupling to a heat bath and the mutual static interaction of
the spins the model can be traced back exactly to a Ginzburg Landau functional
when the interaction is of long range order. The dependence of the correlation
length on the temperature and on the probability is calculated. In case
that the spins are subject to flip processes the correlation length disappears
for each finite temperature. In the exchange dominated case the system is
strongly correlated for each temperature.Comment: 9 pages, Revte
On the Whitney distortion extension problem for and and its applications to interpolation and alignment of data in
Let , open. In this paper we provide a sharp
solution to the following Whitney distortion extension problems: (a) Let
be a map. If is compact (with some
geometry) and the restriction of to is an almost isometry with small
distortion, how to decide when there exists a one-to-one and
onto almost isometry with small distortion
which agrees with in a neighborhood of and a Euclidean motion
away from . (b) Let
be map. If is compact (with some geometry) and the
restriction of to is an almost isometry with small distortion, how
to decide when there exists a one-to-one and onto
almost isometry with small distortion which
agrees with in a neighborhood of and a Euclidean motion away from . Our results complement those of [14,15,20]
where there, is a finite set. In this case, the problem above is also a
problem of interpolation and alignment of data in .Comment: This is part three of four papers with C. Fefferman (arXiv:1411.2451,
arXiv:1411.2468, involve-v5-n2-p03-s.pdf) dealing with the problem of Whitney
type extensions of distortions from certain compact sets to distorted diffeomorphisms on $\Bbb R^n
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