3,182 research outputs found
Semileptonic decays of meson to S-wave charmonium states in the perturbative QCD approach
Inspired by the recent measurement of the ratio of branching fractions
to and final states at the LHCb
detector, we study the semileptonic decays of meson to the S-wave ground
and radially excited 2S and 3S charmonium states with the perturbative QCD
approach. After evaluating the form factors for the transitions , where and denote pseudoscalar and vector S-wave charmonia,
respectively, we calculate the branching ratios for all these semileptonic
decays. The theoretical uncertainty of hadronic input parameters are reduced by
utilizing the light-cone wave function for meson. It is found that the
predicted branching ratios range from up to and could be
measured by the future LHCb experiment. Our prediction for the ratio of
branching fractions is in good
agreement with the data. For decays, the relative
contributions of the longitudinal and transverse polarization are discussed in
different momentum transfer squared regions. These predictions will be tested
on the ongoing and forthcoming experiments.Comment: 12 pages, 3 figures, 5 table
Solar system tests for realistic models with nonminimal torsion-matter coupling
In the previous paper, we have constructed two models with nonminimal
torsion-matter coupling extension, which are successful in describing the
evolution history of the Universe including the radiation-dominated era, the
matter-dominated era, and the present accelerating expansion. Meantime, the
significant advantage of these models is that they could avoid the cosmological
constant problem of CDM. However, the nonminimal coupling between
matter and torsion will affect the tests of Solar system. In this paper, we
study the effects of Solar system in these models, including the gravitation
redshift, geodetic effect and perihelion preccesion. We find that Model I can
pass all three of the Solar system tests. For Model II, the parameter is
constrained by the measure of the perihelion precession of Mercury.Comment: 10 page
Direct CP violation in
We study the direct CP violation in the decay process in the
Standard Model. An interesting mechanism involving the charge symmetry
violating mixing between and is applied to enlarge the CP
asymmetry. With this mechanism, the maximum differential and localized
integrated CP asymmetries can reach and
, respectively, which still leave plenty room
for CP-violating New Physics to be discovered through this process
3D Object Detection for Autonomous Driving: A Survey
Autonomous driving is regarded as one of the most promising remedies to
shield human beings from severe crashes. To this end, 3D object detection
serves as the core basis of such perception system especially for the sake of
path planning, motion prediction, collision avoidance, etc. Generally, stereo
or monocular images with corresponding 3D point clouds are already standard
layout for 3D object detection, out of which point clouds are increasingly
prevalent with accurate depth information being provided. Despite existing
efforts, 3D object detection on point clouds is still in its infancy due to
high sparseness and irregularity of point clouds by nature, misalignment view
between camera view and LiDAR bird's eye of view for modality synergies,
occlusions and scale variations at long distances, etc. Recently, profound
progress has been made in 3D object detection, with a large body of literature
being investigated to address this vision task. As such, we present a
comprehensive review of the latest progress in this field covering all the main
topics including sensors, fundamentals, and the recent state-of-the-art
detection methods with their pros and cons. Furthermore, we introduce metrics
and provide quantitative comparisons on popular public datasets. The avenues
for future work are going to be judiciously identified after an in-deep
analysis of the surveyed works. Finally, we conclude this paper.Comment: 3D object detection, Autonomous driving, Point cloud
Value of superb microvascular imaging ultrasonography in the diagnosis of carpal tunnel syndrome: Compared with color Doppler and power Doppler.
The aim of this study was to compare the value of superb microvascular imaging (SMI) in carpal tunnel syndrome (CTS) with that of color Doppler ultrasonography (CDUS) and power Doppler ultrasonography (PDUS).Fifty patients with symptomatic CTS and 25 healthy volunteers were enrolled. The cross-sectional area (CSA), CDUS score, PDUS score, and SMI score of the median nerve (MN) at the carpal tunnel were recorded. The value of different ultrasonography (US) diagnostic strategies was calculated.The blood flow display ratio in the MN of the healthy volunteers had no statistical difference between CDUS, PDUS, and SMI (20%, 32%, and 48%, respectively, P \u3e.05). The blood flow display ratio for SMI in patients was significantly higher than that of CDUS and PDUS (90%, 52%, and 60%, respectively,
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