20,312 research outputs found
Sigma_c Dbar and Lambda_c Dbar states in a chiral quark model
The S-wave Sigma_c Dbar and Lambda_c Dbar states with isospin I=1/2 and spin
S=1/2 are dynamically investigated within the framework of a chiral constituent
quark model by solving a resonating group method (RGM) equation. The results
show that the interaction between Sigma_c and Dbar is attractive, which
consequently results in a Sigma_c Dbar bound state with the binding energy of
about 5-42 MeV, unlike the case of Lambda_c Dbar state, which has a repulsive
interaction and thus is unbound. The channel coupling effect of Sigma_c Dbar
and Lambda_c Dbar is found to be negligible due to the fact that the gap
between the Sigma_c Dbar and Lambda_c Dbar thresholds is relatively large and
the Sigma_c Dbar and Lambda_c Dbar transition interaction is weak.Comment: 7 pages,2 figures. arXiv admin note: text overlap with
arXiv:nucl-th/0606056 by other author
Isospin breaking and - mixing in the reaction
We make a theoretical study of the and
reactions with an aim to determine the
isospin violation and the mixing of the and resonances.
We make use of the chiral unitary approach where these two resonances appear as
composite states of two mesons, dynamically generated by the meson-meson
interaction provided by chiral Lagrangians. We obtain a very narrow shape for
the production in agreement with a BES experiment. As to the amount
of isospin violation, or and mixing, assuming constant
vertices for the primary and
production, we find results which
are much smaller than found in the recent experimental BES paper, but
consistent with results found in two other related BES experiments. We have
tried to understand this anomaly by assuming an I=1 mixture in the
wave function, but this leads to a much bigger width of the mass
distribution than observed experimentally. The problem is solved by using the
primary production driven by followed by , which induces an extra singularity in the loop functions needed to
produce the and resonances. Improving upon earlier work
along the same lines, and using the chiral unitary approach, we can now predict
absolute values for the ratio which are in fair agreement with experiment. We also show that the same
results hold if we had the resonance or a mixture of these two
states, as seems to be the case in the BES experiment
Electronic States and Magnetism of Mn Impurities and Dimers in Narrow-Gap and Wide-Gap III-V Semiconductors
Electronic states and magnetic properties of single impurity and dimer
doped in narrow-gap and wide-gap - semiconductors have been studied
systematically. It has been found that in the ground state for single
impurity, - complex is antiferromagnetic (AFM) coupling when -
hybridization is large and both the hole level and the
impurity level are close to the midgap; or very weak ferromagnetic (FM)
when is small and both and are deep in the valence band.
In dimer situation, the spins are AFM coupling for half-filled or
full-filled orbits; on the contrast, the Mn spins are double-exchange-like
FM coupling for any -orbits away from half-filling. We propose the strong
{\it p-d} hybridized double exchange mechanism is responsible for the FM order
in diluted - semiconductors
Linear optical implementation of a single mode quantum filter and generation of multi-photon polarization entangled state
We propose a scheme to implement a single-mode quantum filter, which
selectively eliminates the one-photon state in a quantum state
. The vacuum state and the two photon state are
transmitted without any change. This scheme requires single-photon sources,
linear optical elements and photon detectors. Furthermore we demonstrate, how
this filter can be used to realize a two-qubit projective measurement and to
generate multi-photon polarization entangled states.Comment: revision submitted to PR
Vector magnetic field sensing by single nitrogen vacancy center in diamond
In this Letter, we proposed and experimentally demonstrated a method to
detect vector magnetic field with a single nitrogen vacancy (NV) center in
diamond. The magnetic field in parallel with the axis of the NV center can be
obtained by detecting the electron Zeeman shift, while the Larmor precession of
an ancillary nuclear spin close to the NV center can be used to measure the
field perpendicular to the axis. Experimentally, both the Zeeman shift and
Larmor precession can be measured through the fluorescence from the NV center.
By applying additional calibrated magnetic fields, complete information of the
vector magnetic field can be achieved with such a method. This vector magnetic
field detection method is insensitive to temperature fluctuation and it can be
applied to nanoscale magnetic measurement.Comment: 5 pages, 5 figure
The role of the N*(1535) resonance and the pi^- p --> KY amplitudes in the OZI forbidden pi N --> phi N reaction
We study the pi N --> phi N reaction close to the phi N threshold within the
chiral unitary approach, by combining the pi^- p --> K^+ Sigma^-, pi^- p -->
K^0 Sigma^0 and pi^- p --> K^0 Lambda amplitudes with the coupling of the phi
to the K components of the final states of these reactions via quantum loops.
We obtain a good agreement with experiment when the dominant pi^- p --> K^0
Lambda amplitude is constrained with its experimental cross section. We also
evaluate the coupling of the N*(1535) to phi N and find a moderate coupling as
a consequence of partial cancellation of the large KY components of the
N*(1535). We also show that the N*(1535) pole approximation is too small to
reproduce the measured cross section for the pi N --> phi N reaction.Comment: 10 pages, 6 figure
内燃机电磁场点火的耦合装置 Electromagnetic field ignition coupling device for internal combustion engine
一种内燃机电磁场点火的耦合装置,用于将微波能量耦合入发动机气缸内,使微波在气缸内有效地谐振,包括微波传输末端、耦合部分固定装置及耦合器,微波耦合点火装置的同轴传输连接部分的内部尺寸根据气缸的输入阻抗或几何形状直接进行设计,以达到以最小的微波输入和电池功耗产生超过点火所需的临界电场强度。此微波点火系统使微波在汽缸内产生谐振和等离子体,从而击穿并点燃缸内油气混合物,增强燃烧和爆发,并减少排放和油耗。直接适用于汽油机,也能以柴油、天然气、压缩或液化天然气、液化石油气、生物或可再生油,以及混合燃料作为微波点火发动机的燃料。并且该耦合点火系统的造价和现有的火花塞相差无几,容易制造和安装,且运行成本要求低。
An electromagnetic field ignition coupling device for an internal combustion engine is used for coupling microwave energy into an engine cylinder, so as to achieve effective microwave resonance in the cylinder. The coupling device includes a microwave transmission terminal, a coupling part fixing device and a coupler, wherein the internal dimensions of a coaxial transmission connection part of a microwave coupling ignition device are directly designed according to the input impedance or geometric shape of the cylinder, so that an electric field intensity higher than the critical electric field intensity necessary for ignition can be achieved by the minimum microwave input and battery power consumption. In the microwave ignition system, microwave generates resonance and plasmas in the cylinder for breakdown and combustion of oil-gas mixers in the cylinder, so as to improve combustion and detonation and reduce emissions and oil consumption. The coupling device can be directly applied to gasoline engines, and a microwave ignition engine can be fueled by diesel, natural gas, compressed or liquefied natural gas, liquefied petroleum gas, bio-oil, reclaimed oil or mixed fuels. The manufacture cost of the coupling ignition system is almost the same as that of the conventional ignition plug, the manufacture and installation are easy, and the operating cost is low
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