6,955 research outputs found
Estimates for X(4350) Decays from the Effective Lagrangian Approach
The strong and electromagnetic decays of with quantum numbers and have been studied by using the effective Lagrangian
approach. The coupling constant between and
is determined with the help of the compositeness condition which means that
is a bound state of . Other coupling
constants applied in the calculation are determined phenomenologically. Our
numerical results show that, using the present data within the present model,
the possibility that is a molecule can not
be ruled out.Comment: 15 pages, 4 eps figure
Precision measurement of charge number with optomechanically induced transparency
We propose a potentially practical scheme to precisely measure the charge
numbers of small charged objects by optomechanical systems using
optomechanically induced transparency (OMIT). In contrast to the conventional
measurements based on the noise backaction on the optomechanical systems, our
scheme makes use of the small deformation of the mechanical resonator sensitive
to the charge number of the nearby charged object, which could achieve the
detection of a single charge. The relationship between the charge number and
the window width of the OMIT is investigated and the feasibility of the scheme
is justified by numerical simulation using currently available experimental
values.Comment: 6 pages,4 figure
Ambiguities in recurrence-based complex network representations of time series
Recently, different approaches have been proposed for studying basic
properties of time series from a complex network perspective. In this work, the
corresponding potentials and limitations of networks based on recurrences in
phase space are investigated in some detail. We discuss the main requirements
that permit a feasible system-theoretic interpretation of network topology in
terms of dynamically invariant phase-space properties. Possible artifacts
induced by disregarding these requirements are pointed out and systematically
studied. Finally, a rigorous interpretation of the clustering coefficient and
the betweenness centrality in terms of invariant objects is proposed
Large Electronic Anisotropy and Enhanced Chemical Activity of Highly Rippled Phosphorene
We investigate the electronic structure and chemical activity of rippled
phosphorene induced by large compressive strains via first-principles
calculation. It is found that phosphorene is extraordinarily bendable, enabling
the accommodation of ripples with large curvatures. Such highly rippled
phosphorene shows a strong anisotropy in electronic properties. For ripples
along the armchair direction, the band gap changes from 0.84 to 0.51 eV for the
compressive strain up to -20% and further compression shows no significant
effect, for ripples along the zigzag direction, semiconductor to metal
transition occurs. Within the rippled phosphorene, the local electronic
properties, such as the modulated band gap and the alignments of frontier
orbitals, are found to be highly spatially dependent, which may be used for
modulating the injection and confinement of carriers for optical and
photovoltaic applications. The examination of the interaction of a physisorbed
NO molecule with the rippled phosphorene under different compressive strains
shows that the chemical activities of the phosphorene are significantly
enhanced at the top and bottom peaks of the ripples, indicated by the enhanced
adsorption and charge transfer between them. All these features can be ascribed
to the effect of curvatures, which modifies the orbital coupling between atoms
at the ripple peaks
Observation of First-Order Metal-Insulator Transition without Structural Phase Transition in VO_2
An abrupt first-order metal-insulator transition (MIT) without structural
phase transition is first observed by current-voltage measurements and
micro-Raman scattering experiments, when a DC electric field is applied to a
Mott insulator VO_2 based two-terminal device. An abrupt current jump is
measured at a critical electric field. The Raman-shift frequency and the
bandwidth of the most predominant Raman-active A_g mode, excited by the
electric field, do not change through the abrupt MIT, while, they, excited by
temperature, pronouncedly soften and damp (structural MIT), respectively. This
structural MIT is found to occur secondarily.Comment: 4 pages, 4 figure
Classical Dynamics of Anyons and the Quantum Spectrum
In this paper we show that (a) all the known exact solutions of the problem
of N-anyons in oscillator potential precisely arise from the collective degrees
of freedom, (b) the system is pseudo-integrable ala Richens and Berry. We
conclude that the exact solutions are trivial thermodynamically as well as
dynamically.Comment: 19 pages, ReVTeX, IMSc/93/0
Correlation between 3:2 QPO pairs and Jets in Black Hole X-ray Binaries
We argue, following our earlier works (the "CEBZMC model"), that the
phenomenon of twin peak high frequency quasi-periodic oscillations (QPOs)
observed in black hole X-ray binaries is caused by magnetic coupling (MC)
between accretion disk and black hole (BH). Due to MC, two bright spots occur
at two separate radial locations r_{in} and r_{out} at the disk surface,
energized by a kind of the Blandford-Znajek mechanism (BZ). We assume,
following the Kluzniak-Abramowicz QPO resonance model, that Keplerian
frequencies at these two locations are in the 3:2 ratio. With this assumption,
we estimate the BH spins in several sources, including GRO J1655-40, GRS
1915+105, XTE J1550-564, H1743-322 and Sgr A*. We give an interpretation of the
"jet line" in the hardness-intensity plane discussing the parameter space
consisting of the BH spin and the power-law index for the variation of the
large-scale magnetic field in the disk. Furthermore, we propose a new scenario
for the spectral state transitions in BH X-ray binaries based on fluctuation in
densities of accreting plasma from a companion star.Comment: 17 pages, 6 figures, accepted by AP
A Wave Function Describing Superfluidity in a Perfect Crystal
We propose a many-body wave function that exhibits both diagonal and
off-diagonal long-range order. Incorporating short-range correlations due to
interatomic repulsion, this wave function is shown to allow condensation of
zero-point lattice vibrations and phase rigidity. In the presence of an
external velocity field, such a perfect crystal will develop non-classical
rotational inertia, exhibiting the supersolid behavior. In a sample calculation
we show that the superfluid fraction in this state can be as large as of order
0.01 in a reasonable range of microscopic parameters. The relevance to the
recent experimental evidence of a supersolid state by Chan and Kim is
discussed.Comment: final version to be published in Journal of Statistical Mechanics:
Theory and Experimen
Commensurate lock-in and incommensurate supersolid phases of hardcore bosons on anisotropic triangular lattices
We investigate the interplay between commensurate lock-in and incommensurate
supersolid phases of the hardcore bosons at half-filling with anisotropic
nearest-neighbor hopping and repulsive interactions on triangular lattice. We
use numerical quantum and variational Monte Carlo as well as analytical
Schwinger boson mean-field analysis to establish the ground states and phase
diagram. It is shown that, for finite size systems, there exist a series of
jumps between different supersolid phases as the anisotropy parameter is
changed. The density ordering wavevectors are locked to commensurate values and
jump between adjacent supersolids. In the thermodynamic limit, however, the
magnitude of these jumps vanishes leading to a continuous set of novel
incommensurate supersoild phases.Comment: 5 pages, 5 figures, added new results, changed title and conclusio
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