19,302 research outputs found
Some thoughts on constructing a microscopic theory with holographic degrees of freedom
Holographic principle states that the maximum entropy of a system is its
boundary area in Planck units. However, such a holographic entropy cannot be
realized by the conventional quantum field theory. We need a new microscopic
theory which naturally possesses all the holographic degrees of freedom. In
this paper, we provide some preliminary thoughts on how to construct a theory
with holographic degrees of freedom. It may shed light on the understanding of
quantum properties of gravity and the early stage of the universe.Comment: 6 pages, typos correcte
The utmost distance for quantum entanglement
A common viewpoint is that a particle could be quantum entangled with another
particle arbitrarily far away. But in this paper we suggest that there is an
utmost distance for the existence of quantum entanglement between two
particles, beyond which the initial quantum entanglement would be broken by
some quantum gravitational effect. The utmost distance is proposed to be
, where is the quantum
wavelength of the particles and is the Planck
length. The most probable value of the parameter is or . As
other quantum-gravitational effects, this effect is very weak and hard to be
detected in foreseeable experiment.Comment: 4 pages, 1 figure, 1 tabl
Effects of Pressure on the Electronic Structures of LaOFeP
We studied the electronic structures of LaOFeP under applied pressure using
first-principles calculations. The electronic density of states at the Fermi
level decreases continuously with increasing pressure. The electron branches of
Fermi surfaces are rather robust to pressure, while the hole branches change
significantly. Two hole surfaces shrink into small ellipsoid-like surfaces and
disappear finally, at which the applied pressure is ~ 74.7 GPa. The pressure
response can be understood by the band structures around the Fermi level.
Comparative studies reveal that the disappearance of hole surfaces is mainly
due to the compression of the FeP layer along the c-axis of unit cell.Comment: 26 pages, 9 figure
Does the bottomonium counterpart of exist?
A narrow line shape peak at about 10615 MeV, just above the threshold in the
channel, which can be regarded as the signal of bottomonium
counterpart of , , is predicted by using the extended Friedrichs
scheme. Though a virtual state is found at about 10593 MeV in this scheme, we
point out that the peak is contributed mainly by the coupling form factor,
which comes from the convolution of the interaction term and meson wave
functions including the one from , but not mainly by the
virtual-state pole. In this picture, the reason why signal is not
observed in the and channels can
also be understood. The mass and width are found to be about
10771 MeV and 6 MeV, respectively and a dynamically generated broad resonance
is also found with its mass and width at about 10672 MeV and 78 MeV,
respectively. The line shapes of these two states are also affected by the form
factor effect. Thus, this study also emphasizes the importance of the structure
of the wave functions of high radial excitations in the analysis of the line
shapes, and provides a caveat that some signals may be generated from the
structures of the form factors rather than from poles.Comment: 5 pages, 3 figures; v2, the final published versio
Randomness versus specifics for word-frequency distributions
The text-length-dependence of real word-frequency distributions can be
connected to the general properties of a random book. It is pointed out that
this finding has strong implications, when deciding between two conceptually
different views on word-frequency distributions, i.e. the specific
`Zipf's-view' and the non-specific `Randomness-view', as is discussed. It is
also noticed that the text-length transformation of a random book does have an
exact scaling property precisely for the power-law index , as opposed
to the Zipf's exponent and the implication of this exact scaling
property is discussed. However a real text has and as a consequence
increases when shortening a real text. The connections to the
predictions from the RGF(Random Group Formation) and to the infinite
length-limit of a meta-book are also discussed. The difference between
`curve-fitting' and `predicting' word-frequency distributions is stressed. It
is pointed out that the question of randomness versus specifics for the
distribution of outcomes in case of sufficiently complex systems has a much
wider relevance than just the word-frequency example analyzed in the present
work.Comment: 9 pages, 7 figure
Coherent state path integral approach to correlated electron systems with deformed Hubbard operators: from Fermi liquid to Mott insulator
In strongly correlated electron systems the constraint which prohibits the
double electron occupation at local sites can be realized by either the
infinite Coulomb interaction or the correlated hopping interaction described by
the Hubbard operators, but they both render the conventional field theory
inapplicable. Relaxing such the constraint leads to a class of correlated
hopping models based on the deformed Hubbard operators which smoothly
interpolate the locally free and strong coupling limits by a tunable
interaction parameter . Here we propose a coherent state
path integral approach appropriate to the deformed Hubbard operators for {\it
arbitrary} . It is shown that this model system exhibits the
correlated Fermi liquid behavior characterized by the enhanced Wilson ratio for
all . It is further found that in the presence of on-site Coulomb
interaction a finite Mott gap appears between the upper and lower Hubbard
bands, with the upper band spectral weight being heavily reduced by .
Our approach stands in general spatial dimensions and reveals an unexpected
interplay between the correlated hopping and the Coulomb repulsion.Comment: 9 pages, 5 figures (including several appendices
Comprehending Isospin breaking effects of in a Friedrichs-model-like scheme
Recently, we have shown that the state can be naturally generated
as a bound state by incorporating the hadron interactions into the
Godfrey-Isgur quark model using the Friedrichs-like model combined with the QPC
model, in which the wave function for the as a combination of the
bare state and the continuum states can also be obtained. Under this
scheme, we now investigate the isospin breaking effect of in its
decays to and . By Considering its
dominant continuum parts coupling to and through
the quark rearrangement process, one could obtain the reasonable ratio of
. It is also shown that the invariant mass
distributions in the decays could be understood
qualitatively at the same time. This scheme may provide more insight to
understand the enigmatic nature of the state.Comment: 13 pages, 4 figure
Destination Choice Game: A Spatial Interaction Theory on Human Mobility
With remarkable significance in migration prediction, global disease
mitigation, urban planning and many others, an arresting challenge is to
predict human mobility fluxes between any two locations. A number of methods
have been proposed against the above challenge, including the gravity model,
the intervening opportunity model, the radiation model, the population-weighted
opportunity model, and so on. Despite their theoretical elegance, all models
ignored an intuitive and important ingredient in individual decision about
where to go, that is, the possible congestion on the way and the possible
crowding in the destination. Here we propose a microscopic mechanism underlying
mobility decisions, named destination choice game (DCG), which takes into
account the crowding effects resulted from spatial interactions among
individuals. In comparison with the state-of-the-art models, the present one
shows more accurate prediction on mobility fluxes across wide scales from
intracity trips to intercity travels, and further to internal migrations. The
well-known gravity model is proved to be the equilibrium solution of a
degenerated DCG neglecting the crowding effects in the destinations.Comment: 18 pages, 9 figure
The origin of light scalar resonances
We demonstrate how most of the light spectrum below
and their decays can be consistently described by the
unitarized quark model incorporating the chiral constraints of Adler zeros and
taking SU(3) breaking effects into account. These resonances appear as poles in
the complex plane in a unified picture as states strongly
dressed by hadron loops. Through the large analysis, these resonances are
found to naturally separate into two kinds: are dynamically generated and run away from the real axis as
increases, while the others move towards the seeds. In this picture,
the line shape of is produced by a broad pole below the
threshold, and exhibits characteristics similar to the and .Comment: 7 pages, 12 figures, Revtex4-1. Significantly revised and expanded
version. The main result not change
Understanding , , and in a Friedrichs-model-like scheme
We developed a Friedrichs-model-like scheme in studying the hadron resonance
phenomenology and present that the hadron resonances might be regarded as the
Gamow states produced by a Hamiltonian in which the bare discrete state is
described by the result of usual quark potential model and the interaction part
is described by the quark pair creation model. In a one-parameter calculation,
the , , and state could be simultaneously produced
with a quite good accuracy by coupling the three P-wave states,
, , predicted in the
Godfrey-Isgur model to the , , continuum
states. At the same time, we predict that the state is at about 3902
MeV with a pole width of about 54 MeV. In this calculation, the state
has a large compositeness. This scheme may shed more light on the long-standing
problem about the general discrepancy between the prediction of the quark model
and the observed values, and it may also provide reference for future search
for the hadron resonance state.Comment: 5 pages, 1 figure; A mistake was found in the numerical calculation
and the numerical results change a little. The qualitative discussion and
conclusion not change
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