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21.
Reinvestigating B → PV decays by including contributions from ?B2 with the perturbative QCD approach 下载免费PDF全文
Considering the B mesonic wave function \begin{document}$ {\phi}_{B2} $\end{document} ![]()
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, \begin{document}$ B {\to} PV $\end{document} ![]()
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decays are restudied in the leading order for three scenarios using the perturbative QCD approach within the standard model, where \begin{document}$ P = {\pi} $\end{document} ![]()
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and K, and V denotes the ground \begin{document}$S U(3)$\end{document} ![]()
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vector mesons. It is found that contributions from \begin{document}$ {\phi}_{B2} $\end{document} ![]()
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can enhance most branching ratios and are helpful for improving the overall consistency of branching ratios between the updated calculations and available data, although there are still several discrepancies between the experimental and theoretical results. 相似文献
22.
A one-dimensional quantum hydrodynamic model (or quantum Euler-Poisson system) for semiconductors with initial boundary conditions is considered for general pressure-density function. The existence and uniqueness of the classical solution of the corresponding steady-state quantum hydrodynamic equations is proved. Furthermore, the global existence of classical solution, when the initial datum is a perturbation of the steady-state solution, is obtained. This solution tends to the corresponding steady-state solution exponentially fast as the time tends to infinity. 相似文献
23.
The local well-posedness of the Cauchy problem for the coupled Hirota equations is established in Sobolev spaces Hs×Hs by the Fourier restriction norm method. 相似文献
24.
25.
Junfeng Sun Dongsheng Du Yueling Yang 《The European Physical Journal C - Particles and Fields》2009,60(1):107-117
The B
c
→J/ψ
π, η
c
π decays are studied with the perturbative QCD approach. It is found that the form factors
and
for the B
c
→J/ψ, η
c
transitions and the branching ratios are sensitive to the parameters ω, v, f
J/ψ
and
, where ω and v are the parameters of the charmonium wave functions for a Coulomb potential and the harmonic-oscillator potential, respectively,
and f
J/ψ
and
are the decay constants of the J/ψ and η
c
mesons, respectively. The large branching ratios and the clear signals of the final states make the B
c
→J/ψ
π, η
c
π decays the prospective channels for measurements at the hadron colliders. 相似文献
26.
Changmei?Wei Yueling?Zhang Hongjun?Zhu Jintang?WangEmail author 《Journal of chemical crystallography》2005,35(7):561-564
The guanidinium compound 4-guanidino-2-hydroxybenzoic acid, crystallizes in the orthorhombic space group Pbac with a = 8.090(2) Å, b = 12.470(3) Å, c = 16.430(3) Å, and Φcalc = 1.564 Mg/m3 for Z = 8. The three-dimensional network is constructed through hydrogen bonds, electrostatic interactions and weak π–π stacking interaction among the guanidinium, carboxyl and hydroxy groups in the title compound. 相似文献
27.
28.
生物单胺包括儿茶酚胺类以及5-羟色胺等,在中枢神经系统中扮演着非常关键的角色,也是临床上诊断神经内分泌肿瘤疾病的重要生物标志物。由于这类单胺类物质的强化学极性导致传统吸附材料对其吸附效果不佳,从复杂生物样本中同时检测更多的生物单胺存在挑战性。该文建立了一种基于聚冠醚纳米纤维在线固相萃取检测尿液中3种儿茶酚胺(多巴胺、肾上腺素、去甲肾上腺素)和5-羟色胺的方法。采用静电纺丝法制备聚二苯并-18-冠-6醚-聚苯乙烯复合纳米纤维(PCE-PS),制成装填纤维的固相萃取(PFSPE)柱,再将PFSPE柱与HPLC进行在线联用。该在线PFSPE-HPLC方法采用双三元泵进行样品富集净化和分析,左泵连接PFSPE柱,进行样品富集净化;右泵连接分析柱进行样品分离检测。控制切换阀的切换,实现样品富集后洗脱至分析柱中分离检测。结果表明,在线PFSPE-HPLC检测尿液儿茶酚胺(多巴胺、肾上腺素、去甲肾上腺素)和5-羟色胺在1~200 ng/mL范围内有良好的线性关系,线性相关系数达0.996以上。3种儿茶酚胺和5-羟色胺的检出限(S/N=3)分别为1和2.5 ng/mL,定量限(S/N=10)分别为2.5和5 ng/mL。空白尿液和实际尿液加标回收率在83.5%~117.7%之间,日内精密度<10%。PCE-PS复合纳米纤维在多次使用后无明显变化,具有良好的稳定性,可重复使用达95次以上。在线PFSPE-HPLC方法能够集样品在线前处理与分析检测于一体,省时省力,实现分析过程的高度自动化。该方法成功应用于尿液中3种儿茶酚胺和5-羟色胺的检测,可以为临床上相关疾病检测诊断和研究提供有力的技术支持。 相似文献
29.
The Cauchy problem for a nonlocal perturbation of KdV equation is considered by the Fourier restriction norm method. Local
well-posedness for initial data in and global results for data in are obtained.
The second author was supported by the National Natural Science Foundation of China Grant No.10526011. 相似文献
30.
In this paper, some results on the pathwise
exponential stability are established for the weak solutions of
stochastic 2D Navier-Stokes equation driven by noise. Also,
some results and comments concerning the stabilizability and
stabilization of these equations are stated. 相似文献