76,713 research outputs found
Semileptonic decays in the light-cone QCD sum rules
Semileptonic () decays are investigated systematically in the
light-cone QCD sum rules. Special emphasis is put on the LCSR calculation on
weak form factors with an adequate chiral current correlator, which turns out
to be particularly effective to control the pollution by higher twist
components of spectator mesons. The result for each channel depends on the
distribution amplitude of the the producing meson. The leading twist
distribution amplitudes of the related heavy mesons and charmonium are worked
out by a model approach in the reasonable way. A practical scenario is
suggested to understand the behavior of weak form factors in the whole
kinematically accessible ranges. The decay widths and branching ratios are
estimated for several () decay modes of current interest.Comment: 8 pages, talk given by the first arthur at 4th International
Conference on Flavor Physics (ICFP 2007), Beijing, China, Sept 24-28, 200
Improved approach to the heavy-to-light form factors in the light-cone QCD sum
A systematic analysis shows that the main uncertainties in the form factors
are due to the twist-3 wave functions of the light mesons in the light-cone QCD
sum rules. We propose an improved approach, in which the twist-3 wave functions
doesn't make any contribution and therefore the possible pollution by them can
be avoided, to re-examine semileptonic form factors. Also, a
comparison between the previous and our results from the light-cone QCD sum
rules is made. Our method will be beneficial to the precise extracting of
from the experimental data on the processes .Comment: New version to appear in PR
On Binary Matroid Minors and Applications to Data Storage over Small Fields
Locally repairable codes for distributed storage systems have gained a lot of
interest recently, and various constructions can be found in the literature.
However, most of the constructions result in either large field sizes and hence
too high computational complexity for practical implementation, or in low rates
translating into waste of the available storage space. In this paper we address
this issue by developing theory towards code existence and design over a given
field. This is done via exploiting recently established connections between
linear locally repairable codes and matroids, and using matroid-theoretic
characterisations of linearity over small fields. In particular, nonexistence
can be shown by finding certain forbidden uniform minors within the lattice of
cyclic flats. It is shown that the lattice of cyclic flats of binary matroids
have additional structure that significantly restricts the possible locality
properties of -linear storage codes. Moreover, a collection of
criteria for detecting uniform minors from the lattice of cyclic flats of a
given matroid is given, which is interesting in its own right.Comment: 14 pages, 2 figure
Biorthonormal Matrix-Product-State Analysis for Non-Hermitian Transfer-Matrix Renormalization-Group in the Thermodynamic Limit
We give a thorough Biorthonormal Matrix-Product-State (BMPS) analysis of the
Transfer-Matrix Renormalization-Group (TMRG) for non-Hermitian matrices in the
thermodynamic limit. The BMPS is built on a dual series of reduced
biorthonormal bases for the left and right Perron states of a non-Hermitian
matrix. We propose two alternative infinite-size Biorthonormal TMRG (iBTMRG)
algorithms and compare their numerical performance in both finite and infinite
systems. We show that both iBTMRGs produce a dual infinite-BMPS (iBMPS) which
are translationally invariant in the thermodynamic limit. We also develop an
efficient wave function transformation of the iBTMRG, an analogy of McCulloch
in the infinite-DMRG [arXiv:0804.2509 (2008)], to predict the wave function as
the lattice size is increased. The resulting iBMPS allows for probing bulk
properties of the system in the thermodynamic limit without boundary effects
and allows for reducing the computational cost to be independent of the lattice
size, which are illustrated by calculating the magnetization as a function of
the temperature and the critical spin-spin correlation in the thermodynamic
limit for a 2D classical Ising model.Comment: 14 pages, 9 figure
The Form Factor in The Whole Kinematically Accessible Range
A systematic analysis is presented of the form factor in the whole range of momentum transfer , which would be useful to
analyzing the future data on decays and extracting .
With a modified QCD light cone sum rule (LCSR) approach, in which the
contributions cancel out from the twist 3 wavefunctions of meson, we
investigate in detail the behavior of at small and intermediate
and the nonperturbative quantity
is the decay constant of meson and
the strong coupling), whose numerical
result is used to study dependence of at large in
the single pole approximation. Based on these findings, a form factor model
from the best fit is formulated, which applies to the calculation on
in the whole kinematically accessible range. Also, a comparison is made with
the standard LCSR predictions.Comment: 11 pages, Latex, 1 eps figure, Final version to appear in Phys.Rev.
Monotone Grid Drawings of Planar Graphs
A monotone drawing of a planar graph is a planar straight-line drawing of
where a monotone path exists between every pair of vertices of in some
direction. Recently monotone drawings of planar graphs have been proposed as a
new standard for visualizing graphs. A monotone drawing of a planar graph is a
monotone grid drawing if every vertex in the drawing is drawn on a grid point.
In this paper we study monotone grid drawings of planar graphs in a variable
embedding setting. We show that every connected planar graph of vertices
has a monotone grid drawing on a grid of size , and such a
drawing can be found in O(n) time
Hydrodynamics of superfluids confined in blocked rings and wedges
Motivated by many recent experimental studies of non-classical rotational
inertia (NCRI) in superfluid and supersolid samples, we present a study of the
hydrodynamics of a superfluid confined in the two-dimensional region
(equivalent to a long cylinder) between two concentric arcs of radii and
() subtending an angle , with . The case
corresponds to a blocked ring. We discuss the methodology to
compute the NCRI effects, and calculate these effects both for small angular
velocities, when no vortices are present, and in the presence of a vortex. We
find that, for a blocked ring, the NCRI effect is small, and that therefore
there will be a large discontinuity in the moment of inertia associated with
blocking or unblocking circular paths. For blocked wedges () with , we find an unexpected divergence of the velocity at the origin, which
implies the presence of either a region of normal fluid or a vortex for {\it
any} nonzero value of the angular velocity. Implications of our results for
experiments on "supersolid" behavior in solid are discussed. A
number of mathematical issues are pointed out and resolved.Comment: 15 pages, including figures. To appear in Phys. Rev.
Binding-incompetent adenovirus facilitates molecular conjugate-mediated gene transfer by the receptor-mediated endocytosis pathway
Molecular conjugate vectors may be constructed that accomplish high efficiency gene transfer by the receptor-mediated endocytosis pathway. In order to mediate escape from lysosomal degradation, we have incorporated adenoviruses into the functional design of the conjugate. In doing so, however, we have introduced an additional ligand, which can bind to receptors on the cell surface, undermining the potential for cell specific targeting. To overcome this, we have treated the adenovirus with a monoclonal anti-fiber antibody, which renders the virus incapable of binding to its receptor. The result is a multi-functional molecular conjugate vector, which has preserved its binding specificity while at the same time being capable of preventing lysosomal degradation of endosome-internalized conjugate-DNA complexes. This finding indicates that adenoviral binding is not a prerequisite for adenoviral-mediated endosome disruption
Transition Form Factor up to within the Factorization Approach
In the paper, we apply the factorization approach to deal with the
transition form factor in the large recoil
regions. The B-meson wave functions and that include the
three-particle Fock states' contributions are adopted to give a consistent PQCD
analysis of the form factor up to . It has been found that
both the wave functions and can give sizable
contributions to the form factor and should be kept for a better understanding
of the meson decays. Then the contributions from different twist structures
of the kaon wavefunction are discussed, including the -breaking
effects. A sizable contribution from the twist-3 wave function is
found, whose model dependence is discussed by taking two group of parameters
that are determined by different distribution amplitude moments obtained in the
literature. It is also shown that and
, which are more
reasonable and consistent with the light-cone sum rule results in the large
recoil regions.Comment: 22 pages and 6 figure
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