2,263 research outputs found
Semileptonic meson decays to S-wave charmonia and within the covariant light-front approach
In this work, we investigate the semileptonic decays of meson to
, and within the framework of
covariant light-front quark model (CLFQM). We combine the helicity amplitudes
via the corresponding form factors to obtain the branching ratios of the
semileptonic decays , and with
. In view of the anomaly released by the LHCb
collaboration, it is necessary to calculate the ratios with
systematically, which are helpful
to check the lepton flavor universality (LFU). Furthermore, we also take into
account another two physical observables, one is the longitudinal polarization
fraction and the other is the forward-backward asymmetry ,
which can provide new clues to understand the anomaly. Such
theoretical predictions are necessary and interesting, which can be tested in
the future LHCb experiments.Comment: 23 pages, 4 figure
Quasi-two-body decays in the perturbative QCD
In this work we study the quasi-two-body decays in the perturbative QCD (PQCD) approach.
The two-meson distribution amplitudes (DAs) are
introduced to describe the final state interactions of the K \pi pair, which
involve the time-like form factors F_{K\pi}(s) parameterized by the
relativistic Breit-Wigner function and the Gegenbauer polynomials. We calculate
the branching ratios for these quasi-two-body decays, from which one can obtain
the branching raios for the corresponding two-body decays under the narrow
width approximation relation. We find that and have the largest branching ratios, which can reach up to ,
while the branching ratios for other two-body decays are very small and only
about . As we expected that the branching ratios of the
pure annihilation decays are usually small, while in our considered such type
of decays, the channel has the largest branching
ratio, which is near . These results are consistent with the
previously PQCD calculations obtained in the two-body framework, which can be
tested by the future LHCb experiments. For the decays and , we calculate their direct CP
violations and find that is the largest one, which is
possible measured by the present LHCb experiments. For the pure annihilation
type decays, there is no CP violations because only the tree operators are
involved. Furthermore, we also give the differential distributions of the
branching ratios and the direct CP violations for the decays .Comment: 15 pages, 3 figures, 2 table
A Review of Characteristics of Bio-Oils and Their Utilization as Additives of Asphalts
Transforming waste biomass materials into bio-oils in order to partially substitute petroleum asphalt can reduce environmental pollution and fossil energy consumption and has economic benefits. The characteristics of bio-oils and their utilization as additives of asphalts are the focus of this review. First, physicochemical properties of various bio-oils are characterized. Then, conventional, rheological, and chemical properties of bio-oil modified asphalt binders are synthetically reviewed, as well as road performance of bio-oil modified asphalt mixtures. Finally, performance optimization is discussed for bio-asphalt binders and mixtures. This review indicates that bio-oils are highly complex materials that contain various compounds. Moreover, bio-oils are source-depending materials for which its properties vary with different sources. Most bio-oils have a favorable stimulus upon the low temperature performance of asphalt binders and mixtures but exhibit a negative impact on their high-temperature performance. Moreover, a large amount of oxygen element, oxygen-comprising functional groups, and light components in plant-based bio-oils result in higher sensitivity to ageing of bio-oil modified asphalts. In order to increase the performance of bio-asphalts, most research has been limited to adding additive agents to bio-asphalts; therefore, more reasonable optimization methods need to be proposed. Furthermore, upcoming exploration is also needed to identify reasonable evaluation indicators of bio-oils, modification mechanisms of bio-asphalts, and long-term performance tracking in field applications of bio-asphalts during pavement service life
Fumigant Activity of Eight Plant Essential Oils Against Workers of Red Imported Fire Ant, Solenopsis invicta
Plant essential oils from eight plant species were tested for their insecticidal activities against the red imported fire ant, Solenopsis invcita, by using a fumigation bioassay. This study reveals that the mortalities after treatment of the workers of red imported fire ants varied according to the classification of workers, oil type, dosage, and exposure time. Among the essential oils tested, strong insecticidal activity was observed with the essential oils of camphor (Cinnamomum camphora), artemisia annua (Artemisia annua), eucalyptus (Eucalyptus globulus), mugwort (Artemisia argyi), and wintergreen (Ilex chinensis). Ant mortalities from chrysanthemum oil (Dendranthema indicum), turpentine oil (Pinus massoniana), and forsythia oil (Forsythia suspense) treatments were significantly lower than those from the previously mentioned five essential oil treatments. This study showed that camphor, artemisia annua, eucalyptus, mugwort, and wintergreen oils may have potential to be used as substitutes for chemical insecticides
Deep Learning the Effects of Photon Sensors on the Event Reconstruction Performance in an Antineutrino Detector
We provide a fast approach incorporating the usage of deep learning for
evaluating the effects of photon sensors in an antineutrino detector on the
event reconstruction performance therein. This work is an attempt to harness
the power of deep learning for detector designing and upgrade planning. Using
the Daya Bay detector as a benchmark case and the vertex reconstruction
performance as the objective for the deep neural network, we find that the
photomultiplier tubes (PMTs) have different relative importance to the vertex
reconstruction. More importantly, the vertex position resolutions for the Daya
Bay detector follow approximately a multi-exponential relationship with respect
to the number of PMTs and hence, the coverage. This could also assist in
deciding on the merits of installing additional PMTs for future detector plans.
The approach could easily be used with other objectives in place of vertex
reconstruction
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