8,812 research outputs found
Charmless Two-body decays In Soft-Collinear-Effective-Theory
We provide the analysis of charmless two-body decays under the
framework of the soft-collinear-effective-theory (SCET), where denotes a
light vector (pseudoscalar) meson. Besides the leading power contributions,
some power corrections (chiraly enhanced penguins) are also taken into account.
Using the current available and experimental data on
branching fractions and CP asymmetry variables, we find two kinds of solutions
in fit for the 16 non-perturbative inputs which are essential in the
87 and decay channels. Chiraly enhanced penguins can change
several charming penguins sizably, since they share the same topology. However,
most of the other non-perturbative inputs and predictions on branching ratios
and CP asymmetries are not changed too much. With the two sets of inputs, we
predict the branching fractions and CP asymmetries of other modes especially
decays. The agreements and differences with results in QCD
factorization and perturbative QCD approach are analyzed. We also study the
time-dependent CP asymmetries in channels with CP eigenstates in the final
states and some other channels such as and
. In the perturbative QCD approach, the
penguins in annihilation diagrams play an important role. Although
they have the same topology with charming penguins in SCET, there are many
differences between the two objects in weak phases, magnitudes, strong phases
and factorization properties.Comment: 34 pages, revtex, 2 figures, published at PR
boson radiative decays to a -wave quarkonium at NNLO and NLL accuracy
Within the framework of nonrelativistic QCD (NRQCD) factorization formalism,
we compute QCD next-to-next-to-leading order (NNLO) corrections to the helicity
amplitudes as well as the decay width of , where can be
, or . In addition, we resum the
next-to-leading logarithms (NLL) of to all orders of
for the leading-twist helicity amplitude by employing the light-cone
factorization approach. It is worth mentioning that we obtain the analytic
expressions of the truncated NLL at . We find that the
corrections are around 10\% for and
productions, however insignificant for and productions. The
corrections are moderate for charmonium production,
while very small for bottomonium production. Moreover, it is found that the NLL
resummation can considerably alter the NRQCD prediction, especially for
production. Combining the NRQCD and light-cone computation, we make
phenomenological predictions on the decay widths and branching fractions. In
addition, we investigate the dependence of the theoretical results on the heavy
quark mass, and find the branching fraction of monotonically
decreases as increases.Comment: 21 pages, 2 figures, 3 tables. correct typos, add the comparison with
LC models, match the published version in PRD. arXiv admin note: text overlap
with arXiv:2208.1011
Improving Catheter Segmentation & Localization in 3D Cardiac Ultrasound Using Direction-Fused FCN
Fast and accurate catheter detection in cardiac catheterization using
harmless 3D ultrasound (US) can improve the efficiency and outcome of the
intervention. However, the low image quality of US requires extra training for
sonographers to localize the catheter. In this paper, we propose a catheter
detection method based on a pre-trained VGG network, which exploits 3D
information through re-organized cross-sections to segment the catheter by a
shared fully convolutional network (FCN), which is called a Direction-Fused FCN
(DF-FCN). Based on the segmented image of DF-FCN, the catheter can be localized
by model fitting. Our experiments show that the proposed method can
successfully detect an ablation catheter in a challenging ex-vivo 3D US
dataset, which was collected on the porcine heart. Extensive analysis shows
that the proposed method achieves a Dice score of 57.7%, which offers at least
an 11.8 % improvement when compared to state-of-the-art instrument detection
methods. Due to the improved segmentation performance by the DF-FCN, the
catheter can be localized with an error of only 1.4 mm.Comment: ISBI 2019 accepte
Online Multicast Traffic Engineering for Software-Defined Networks
Previous research on SDN traffic engineering mostly focuses on static
traffic, whereas dynamic traffic, though more practical, has drawn much less
attention. Especially, online SDN multicast that supports IETF dynamic group
membership (i.e., any user can join or leave at any time) has not been
explored. Different from traditional shortest-path trees (SPT) and graph
theoretical Steiner trees (ST), which concentrate on routing one tree at any
instant, online SDN multicast traffic engineering is more challenging because
it needs to support dynamic group membership and optimize a sequence of
correlated trees without the knowledge of future join and leave, whereas the
scalability of SDN due to limited TCAM is also crucial. In this paper,
therefore, we formulate a new optimization problem, named Online Branch-aware
Steiner Tree (OBST), to jointly consider the bandwidth consumption, SDN
multicast scalability, and rerouting overhead. We prove that OBST is NP-hard
and does not have a -competitive algorithm for any
, where is the largest group size at any time. We
design a -competitive algorithm equipped with the notion of the
budget, the deposit, and Reference Tree to achieve the tightest bound. The
simulations and implementation on real SDNs with YouTube traffic manifest that
the total cost can be reduced by at least 25% compared with SPT and ST, and the
computation time is small for massive SDN.Comment: Full version (accepted by INFOCOM 2018
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