5,731 research outputs found
Nonleptonic two-body charmless B decays involving a tensor meson in the Perturbative QCD Approach
Two-body charmless hadronic B decays involving a light tensor meson in the
final states are studied in the perturbative QCD approach based on
factorization. From our calculations, we find that the decay branching ratios
for color allowed tree-dominated decays and modes are of order and , respectively.
While other color suppressed tree-dominated decays have very small branching
ratios. In general, the branching ratios of most decays are in the range of
to , which are bigger by one or two orders of magnitude than
those predictions obtained in Isgur-Scora-Grinstein-Wise II model and in the
covariant light-front approach, but consistent with the recent experimental
measurements and the QCD factorization calculations. Since the decays with a
tensor meson emitted from vacuum are prohibited in naive factorization, the
contributions of nonfactorizable and annihilation diagrams are very important
to these decays, which are calculable in our perturbative QCD approach. We also
give predictions to the direct CP asymmetries, some of which are large enough
for the future experiments to measure. Because we considered the mixing between
and , the decay rates are enhanced significantly for some
decays involving meson, even with a small mixing angle.Comment: 26 pages, 2 figure
Conditions for entanglement transformation between a class of multipartite pure states with generalized Schmidt decompositions
In this note we generalize Nielsen's marjoization criterion for the
convertibility of bipartite pure states [Phys. Rev. Lett \textbf{83},
436(1999)] to a special class of multipartite pure states which have
generalized Schmidt decompositions.Comment: 3 pages (Revetex 4), no figures. A brief note on entanglement
transformation. Comments are welcom
Twist-4 contributions to the azimuthal asymmetry in SIDIS
We calculate the differential cross section for the unpolarized
semi-inclusive deeply inelastic scattering (SIDIS) process
in leading order (LO) of perturbative QCD and up to twist-4 in power
corrections and study in particular the azimuthal asymmetry . The
final results are expressed in terms of transverse momentum dependent (TMD)
parton matrix elements of the target nucleon up to twist-4. %Under the maximal
two-gluon correlation approximation, these TMD parton matrix elements in a
nucleus %can be expressed terms of a Gaussian convolution of that in a nucleon
with the width given by the jet transport %parameter inside cold nuclei. We
also apply it to $e^-+A \to e^-+q+X$ and illustrate numerically the nuclear
dependence of the azimuthal asymmetry by using a Gaussian ansatz
for the TMD parton matrix elements.Comment: 9 pages, afigur
Fractional quantum Hall effect at : Ground states, non-Abelian quasiholes, and edge modes in a microscopic model
We present a comprehensive numerical study of a microscopic model of the
fractional quantum Hall system at filling fraction , based on the
disc geometry. Our model includes Coulomb interaction and a semi-realistic
confining potential. We also mix in some three-body interaction in some cases
to help elucidate the physics. We obtain a phase diagram, discuss the
conditions under which the ground state can be described by the Moore-Read
state, and study its competition with neighboring stripe phases. We also study
quasihole excitations and edge excitations in the Moore-Read--like state. From
the evolution of edge spectrum, we obtain the velocities of the charge and
neutral edge modes, which turn out to be very different. This separation of
velocities is a source of decoherence for a non-Abelian quasihole/quasiparticle
(with charge ) when propagating at the edge; using numbers obtained
from a specific set of parameters we estimate the decoherence length to be
around four microns. This sets an upper bound for the separation of the two
point contacts in a double point contact interferometer, designed to detect the
non-Abelian nature of such quasiparticles. We also find a state that is a
potential candidate for the recently proposed anti-Pfaffian state. We find the
speculated anti-Pfaffian state is favored in weak confinement (smooth edge)
while the Moore-Read Pfaffian state is favored in strong confinement (sharp
edge).Comment: 15 pages, 9 figures; Estimate of e/4 quasiparticle/hole coherence
length when propagating along the edge modified in response to a recent
revision of Ref. 25, and minor changes elsewher
Strong decays of heavy baryons in Bethe-Salpeter formalism
In this paper we study the properties of diquarks (composed of and/or
quarks) in the Bethe-Salpeter formalism under the covariant instantaneous
approximation. We calculate their BS wave functions and study their effective
interaction with the pion. Using the effective coupling constant among the
diquarks and the pion, in the heavy quark limit , we calculate
the decay widths of () in the BS formalism under the
covariant instantaneous approximation and then give predictions of the decay
widths .Comment: 41 pages, 1 figure, LaTex2e, typos correcte
Localization of fermionic fields on braneworlds with bulk tachyon matter
Recently, Pal and Skar in [arXiv:hep-th/0701266] proposed a mechanism to
arise the warped braneworld models from bulk tachyon matter, which are endowed
with a thin brane and a thick brane. In this framework, we investigate
localization of fermionic fields on these branes. As in the 1/2 spin case, the
field can be localized on both the thin and thick branes with inclusion of
scalar background. In the 3/2 spin extension, the general supergravity action
coupled to chiral supermultiplets is considered to produce the localization on
both the branes as a result.Comment: 9 pages, no figure
A Modeling Approach to Fiber Fracture in Melt Impregnation
© 2016, Springer Science+Business Media Dordrecht. The effect of process variables such as roving pulling speed, melt temperature and number of pins on the fiber fracture during the processing of thermoplastic based composites was investigated in this study. The melt impregnation was used in this process of continuous glass fiber reinforced thermoplastic composites. Previous investigators have suggested a variety of models for melt impregnation, while comparatively little effort has been spent on modeling the fiber fracture caused by the viscous resin. Herein, a mathematical model was developed for impregnation process to predict the fiber fracture rate and describe the experimental results with the Weibull intensity distribution function. The optimal parameters of this process were obtained by orthogonal experiment. The results suggest that the fiber fracture is caused by viscous shear stress on fiber bundle in melt impregnation mold when pulling the fiber bundle
Detecting Extra Dimension by Helium-like Ions
Considering that gravitational force might deviate from Newton's
inverse-square law and become much stronger in small scale, we present a method
to detect the possible existence of extra dimensions in the ADD model. By
making use of an effective variational wave function, we obtain the
nonrelativistic ground energy of a helium atom and its isoelectronic sequence.
Based on these results, we calculate gravity correction of the ADD model. Our
calculation may provide a rough estimation about the magnitude of the
corresponding frequencies which could be measured in later experiments.Comment: 8 pages, no figures, accepted by Mod. Phys. Lett.
Asymptotics for turbulent flame speeds of the viscous G-equation enhanced by cellular and shear flows
G-equations are well-known front propagation models in turbulent combustion
and describe the front motion law in the form of local normal velocity equal to
a constant (laminar speed) plus the normal projection of fluid velocity. In
level set formulation, G-equations are Hamilton-Jacobi equations with convex
( type) but non-coercive Hamiltonians. Viscous G-equations arise from
either numerical approximations or regularizations by small diffusion. The
nonlinear eigenvalue from the cell problem of the viscous G-equation
can be viewed as an approximation of the inviscid turbulent flame speed .
An important problem in turbulent combustion theory is to study properties of
, in particular how depends on the flow amplitude . In this
paper, we will study the behavior of as at
any fixed diffusion constant . For the cellular flow, we show that
Compared with the inviscid G-equation (), the diffusion dramatically slows
down the front propagation. For the shear flow, the limit
\nit where
is strictly decreasing in , and has zero derivative at .
The linear growth law is also valid for of the curvature dependent
G-equation in shear flows.Comment: 27 pages. We improve the upper bound from no power growth to square
root of log growt
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