185 research outputs found
A Comparative Study of within QCD Sum Rules with Two Typical Correlators up to Next-to-Leading Order
The B-decay constant is an important component for studying -meson
decays, which can be studied through QCD sum rules. We make a detailed
discussion on from two sum rules, i.e. sum rules I and II, which are
derived from the conventional correlator and the correlator with chiral
currents respectively. It is found that these two sum rules are consistent with
each other. However, the sum rules II has less uncertainty sources than that of
sum rules I, and then it can be more accurate if we know the dimension-four
gluon condensate well. It is found that decreases with the increment of
, and to compare with the Belle experimental data on , both sum rules
prefer smaller pole -quark mass, GeV. By varying all the
input parameters in their reasonable region and adding all the uncertainties
together in quadrature, we obtain MeV for sum rules I and
MeV for sum rules II.Comment: 11 pages, 4 figures, 2 tables. To match the printed version. To be
published in Communications in Theoretical Physic
Hyperkahler sigma models on cotangent bundles of Hermitian symmetric spaces using projective superspace
Kahler manifolds have a natural hyperkahler structure associated with (part
of) their cotangent bundles. Using projective superspace, we construct
four-dimensional N = 2 models on the tangent bundles of some classical
Hermitian symmetric spaces (specifically, the four regular series of
irreducible compact symmetric Kahler manifolds, and their non-compact
versions). A further dualization yields the Kahler potential for the
hyperkahler metric on the cotangent bundle.Comment: 47 pages, typos corrected, version accepted by JHE
Charmless Decays Based on the six-quark Effective Hamiltonian with Strong Phase Effects II
We provide a systematic study of charmless decays (
and denote pseudoscalar and vector mesons, respectively) based on an
approximate six-quark operator effective Hamiltonian from QCD. The calculation
of the relevant hard-scattering kernels is carried out, the resulting
transition form factors are consistent with the results of QCD sum rule
calculations. By taking into account important classes of power corrections
involving "chirally-enhanced" terms and the vertex corrections as well as weak
annihilation contributions with non-trivial strong phase, we present
predictions for the branching ratios and CP asymmetries of decays into
PP, PV and VV final states, and also for the corresponding polarization
observables in VV final states. It is found that the weak annihilation
contributions with non-trivial strong phase have remarkable effects on the
observables in the color-suppressed and penguin-dominated decay modes. In
addition, we discuss the SU(3) flavor symmetry and show that the symmetry
relations are generally respected
On the Black-Hole/Qubit Correspondence
The entanglement classification of four qubits is related to the extremal
black holes of the 4-dimensional STU model via a time-like reduction to three
dimensions. This correspondence is generalised to the entanglement
classification of a very special four-way entanglement of eight qubits and the
black holes of the maximally supersymmetric N = 8 and exceptional magic N = 2
supergravity theories.Comment: 32 pages, very minor changes at the start of Sec. 4.1. Version to
appear in The European Physical Journal - Plu
A re-examination of the life and work of A.F.G. Kerr and of his colleagues and friends
Arthur Francis George Kerrâs life is reviewed and related to a previously published account. Kerrâs collecting activity
is analysed using an expanded version of the Thai Biogeography Groupâs database of collections. 8,666 of the total 48,970 collections
are Kerrâs and 3,178 are those of his colleagues and friends. Therefore, the total number of collections made by Kerr and his
acquaintances is likely to be larger and more diverse than previously believed. Mapping of these data using GIS show that Kerrâs
collecting activities focussed on particular regions of Thailand at particular times. Also large areas of the country remained unexplored
by Kerr and his acquaintances: a pattern that, to some extent, persists to this day. The large, but dispersed, archive of Kerrâs
photographs, maps, living collections and correspondence indicate that he was a skilled photographer (taking at least 3,000 images),
cartographer (producing many hand-drawn maps) and exceptionally acute, accurate and detailed observer (filling numerous notebooks
and leaving other records). It is clear that digitising these collections to form an on-line dedicated website is highly desirable
to further progress on the flora of Thailand and surrounding countries and would form an unique record of the social history of early
20thC Thailand
Research on Free Vibration Frequency Characteristics of Rotating Functionally Graded Material Truncated Conical Shells with Eccentric Functionally Graded Material Stringer and Ring Stiffeners
Prunella vulgaris: A comprehensive review of chemical constituents, pharmacological effects and clinical applications.
Prunella vulgaris (PV) is a perennial herb belonging to the Labiate family and is widely distributed in northeastern Asian countries such as Korea, Japan, and China. It is reported to display diverse biological activities including anti-microbial, anti-cancer, and anti-inflammation as determined by in vitro or in vivo studies. So far, about 200 compounds have been isolated from PV plant and majority of these have been characterized mainly as triterpenoids, sterols and flavonoids, followed by coumarins, phenylpropanoids, polysaccharides and volatile oils. This review summarizes and analyzes the current knowledge on the chemical constituents, pharmacological activities, mechanisms of action and clinical applications of the PV plant including its potential as a future medicinal plant. Although some of the chemical constituents of the PV plant and their mechanism of action have been investigated the biological activities of many of these remain unknown and further clinical trials are required to further enhance its reputation as a medicinal plant
Genome-Wide Joint Meta-Analysis of SNP and SNP-by-Smoking Interaction Identifies Novel Loci for Pulmonary Function
Purple nonâsulphur bacteria and plant production: benefits for fertilization, stress resistance and the environment
Purple non-sulphur bacteria (PNSB) are phototrophic microorganisms, which increasingly gain attention in plant production due to their ability to produce and accumulate high-value compounds that are benefi- cial for plant growth. Remarkable features of PNSB include the accumulation of polyphosphate, the pro- duction of pigments and vitamins and the production of plant growth-promoting substances (PGPSs). Scattered case studies on the application of PNSB for plant cultivation have been reported for decades, yet a comprehensive overview is lacking. This review highlights the potential of using PNSB in plant pro- duction, with emphasis on three key performanceindicators (KPIs): fertilization, resistance to stress (biotic and abiotic) and environmental benefits. PNSB have the potential to enhance plant growth performance, increase the yield and quality of edible plant biomass, boost the resistance to environmental stresses, bioremediate heavy metals and mitigate greenhouse gas emissions. Here, the mechanisms responsible for these attributes are discussed. A dis- tinction is made between the use of living and dead PNSB cells, where critical interpretation of existing literature revealed the better performance of living cells. Finally, this review presents research gaps that remain yet to be elucidated and proposes a roadmap for future research and implementation paving the way for a more sustainable crop production
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