24,087 research outputs found
Hidden-Charm Tetraquarks and Charged Zc States
Experimentally several charged axial-vector hidden-charm states were
reported. Within the framework of the color-magnetic interaction, we have
systematically considered the mass spectrum of the hidden-charm and
hidden-bottom tetraquark states. It is impossible to accommodate all the three
charged states , and within the axial vector
tetraquark spectrum simultaneously. Not all these three states are tetraquark
candidates. Moreover, the eigenvector of the chromomagnetic interaction
contains valuable information of the decay pattern of the tetraquark states.
The dominant decay mode of the lowest axial vector tetraquark state is while its and modes are strongly suppressed,
which is in contrast with the fact that the dominant decay mode of
and is and respectively. We emphasize
that all the available experimental information indicates that is a
very promising candidate of the lowest axial vector hidden-charm tetraquark
state
On q-deformed infinite-dimensional n-algebra
The -deformation of the infinite-dimensional -algebra is investigated.
Based on the structure of the -deformed Virasoro-Witt algebra, we derive a
nontrivial -deformed Virasoro-Witt -algebra which is nothing but a
sh--Lie algebra. Furthermore in terms of the pseud-differential operators on
the quantum plane, we construct the (co)sine -algebra and the -deformed
-algebra. We prove that they are the sh--Lie algebras for
the case of even . An explicit physical realization of the (co)sine
-algebra is given.Comment: 22 page
Energy Spectrum Extraction and Optimal Imaging via Dual-Energy Material Decomposition
Inferior soft-tissue contrast resolution is a major limitation of current CT
scanners. The aim of the study is to improve the contrast resolution of CT
scanners using dual-energy acquisition. Based on dual-energy material
decomposition, the proposed method starts with extracting the outgoing energy
spectrum by polychromatic forward projecting the material-selective images. The
extracted spectrum is then reweighted to boost the soft-tissue contrast. A
simulated water cylinder phantom with inserts that contain a series of six
solutions of varying iodine concentration (range, 0-20 mg/mL) is used to
evaluate the proposed method. Results show the root mean square error (RMSE)
and mean energy difference between the extracted energy spectrum and the
spectrum acquired using an energy-resolved photon counting detector(PCD), are
0.044 and 0.01 keV, respectively. Compared to the method using the standard
energy-integrating detectors, dose normalized contrast-to-noise ratio (CNRD)
for the proposed method are improved from 1 to 2.15 and from 1 to 1.88 for the
8 mg/mL and 16 mg/mL iodine concentration inserts, respectively. The results
show CT image reconstructed using the proposed method is superior to the image
reconstructed using the standard method that using an energy-integrating
detector.Comment: 4 pages, 4 figures in The 2015 IEEE Nuclear Science Symposium and
Medical Imaging Conference Recor
Engineering Photon Delocalization in a Rabi Dimer with a Dissipative Bath
A Rabi dimer is used to model a recently reported circuit quantum
electrodynamics system composed of two coupled transmission-line resonators
with each coupled to one qubit. In this study, a phonon bath is adopted to
mimic the multimode micromechanical resonators and is coupled to the qubits in
the Rabi dimer. The dynamical behavior of the composite system is studied by
the Dirac-Frenkel time-dependent variational principle combined with the
multiple Davydov D ans\"{a}tze. Initially all the photons are pumped into
the left resonator, and the two qubits are in the down state coupled with the
phonon vacuum. In the strong qubit-photon coupling regime, the photon dynamics
can be engineered by tuning the qubit-bath coupling strength and
photon delocalization is achieved by increasing . In the absence of
dissipation, photons are localized in the initial resonator. Nevertheless, with
moderate qubit-bath coupling, photons are delocalized with quasiequilibration
of the photon population in two resonators at long times. In this case, high
frequency bath modes are activated by interacting with depolarized qubits. For
strong dissipation, photon delocalization is achieved via frequent
photon-hopping within two resonators and the qubits are suppressed in their
initial down state.Comment: 11 pages, 11 figure
Spectral properties, generation order parameters and luminosities for spin-powered X-ray pulsars
We show the spectral properties of 15 spin-powered X-ray pulsars, and the
correlation between the average power-law photon index and spin-down rate.
Generation order parameters (GOPs) based on polar-cap models are introduced to
characterize the X-ray pulsars. We calculate three definitions of generation
order parameters due to the different effects of magnetic and electric fields
on photon absorption during cascade processes, and study the relations between
the GOPs and spectral properties of X-ray pulsars. There exists a possible
correlation between the photon index and GOP in our pulsar sample. Furthermore,
we present a method due to the concept of GOPs to estimate the non-thermal
X-ray luminosity for spin-powered pulsars. Then X-ray luminosity is calculated
in the context of our polar-cap accelerator model which is well consistent with
the most observed X-ray pulsar data. The ratio between X-ray luminosity
estimated by our method and the pulsar's spin-down power is well consistent
with the feature.Comment: 20 pages, 8 figures, 1 table, revised version for the publication in
Ap
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