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We calculate the branching ratio of B → J/ψπ0 with a mixed formalism that combines the QCDimproved factorization and the perturbative QCD approaches.The result is consistent with experimental data.The quite small penguin contribution in B → J/ψπ0 decay can be calculated with this method.We suggest two methods to extract the weak phase β.One is through the dependence of the mixing induced CP asymmetry SJ/ψπ0 on the weak phase β,the other is from the relation of the total asymmetry ACP with the weak phase β.Our results show that the deviation ΔSJ/ψπ0 of the mixing induced CP asymmetry from sin(-2β) is of O(10-3) and has much less uncertainty.The above O(10-3) deviation can provide a good reference for identifying new physics. 相似文献
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本文提出一种新型函数光子晶体, 其折射率是空间位置函数. 由费马原理, 我们给出光在一维、 二维和三维函数光子晶体中的运动方程, 以及一维函数光子晶体的色散关系、 带隙结构和透射率, 再利用传输矩阵理论研究函数光子晶体周期数、 入射角和介质层的厚度等对透射率和禁带结构的影响, 计算发现通过选择不同的折射率空间分布函数, 可以得到比传统光子晶体更宽或更窄的禁带结构. 这样为我们设计不同带隙结构的光子晶体提供理论依据. 相似文献
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一维新型阶梯函数光子晶体透射特性 总被引:1,自引:1,他引:0
研究了阶梯型折射率n22、n11(阶梯分布高度)的大小、对应的分布厚度、不同入射角以及缺陷模对阶梯函数型光子晶体透射特性的影响.由费马原理给出光在函数光子晶体中的运动方程,再由电磁传播理论给出函数光子晶体的传输矩阵,进一步推导出函数光子晶体的透射率以及电场分布的表达式.研究表明,1)随n22,n11大小或者厚度改变,其禁带变宽;2)随光的入射角增加,其禁带变窄;3)当加入缺陷层时,随着缺陷层介质折射率增加,缺陷模强度减小且位置发生红移;4)在函数光子晶体中,缺陷层前电场分布保持不变,而在缺陷层处以及之后的电场强度都明显增强,这不同于常规光子晶体的电场分布仅在缺陷层处局域增强. 相似文献
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Phenomena of electron, neutron, atomic and molecular diffraction have been studied in many experiments, and these experiments are explained by many theoretical works. We study neutron single-slit diffraction with a quantum mechanical approach. It is found that the obvious diffraction patterns can be obtained when the single- slit width a is in the range of 3λ - 60λ. We also lind a new quantum effect of the thickness of single-slit which can make a large impact on the diffraction pattern. The new quantum effect predicted in our work can be tested by the neutron single-slit diffraction experiment. 相似文献
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We calculate the D → η transition form factor in light-cone sum rules by taking improved current correlators to avoid the pollution from the twist-3 wave function. We get consistent results of the D+ → η(')l+νl decays with the experimental data. By comparing the difference between the results of the branching ratios of D+ → η(')l+νl from a two-pole parameterization model and from a BZ parameterization model, we find that the two-pole model and the BZ model are comparably believable. One way is supposed for the determination of the η-η' mixing angle from the dependence of the branching ratios of D+ → η(')l+νl decays on the η-η' mixing angle. 相似文献
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用传输矩阵法对含缺陷层的一维光子晶体的吸收特性进行了系统的研究。取介质层为非金属介质,缺陷层为金属介质,给出实际材料构成的光子晶体吸收率与波长的关系曲线,又对任意介质构成的光子晶体吸收特性进行了研究,即分别研究了入射角的变化、缺陷层折射率虚部的变化、介质层折射率的变化、介质层厚度的变化以及光子晶体周期结构的变化对光子晶体吸收特性的影响,得到了一些有价值的结论。通过调节光子晶体的一些参数,就可以发现这些参数对光子晶体吸收率的影响,从而为光子晶体的设计和制备提供了重要的理论依据。 相似文献