The nonleptonic two body B decays involving a light tensor meson in final states

The nonleptonic two body Bu,d,s,c decays involving a light tensor meson in final states are studied in the perturbative QCD approach based on kT factorization. The decay modes with a tensor meson emitted, are prohibited in naive factorization, since the emission diagram with a tensor meson produced from vacuum is vanished. While contributions from the so-called hard scattering emission diagrams and annihilation type diagrams are important and calculable in the perturbative QCD approach. The branching ratios of most decays are in the range of 10-4-10-8, which are bigger by 1 or 2 orders of magnitude than the predictions given by the naive factor- ization, but consistent with the predictions from the QCD factorization and the recent experimental measurements. We also give the predictions for the direct CP asymmetries, some of which are large enough for the future experiments to measure. We also find that, even with a small mixing angle, the mixing between f2 and f′2 can bring remarkable changes to both branching ratios and the direct CP asymmetries for some decays involving f2（′） mesons. For decays with a vector meson and a tensor meson in final states, we predict a large percentage of transverse polarization contributions due to the contributions of the orbital angular momentum of the tensor mesons.     

The nonleptonic two body B decays involving a light tensor meson in final states

The nonleptonic two body \(B_{u,d,s,c}\) decays involving a light tensor meson in final states are studied in the perturbative QCD approach based on \(k_{\mathrm{T}}\) factorization. The decay modes with a tensor meson emitted, are prohibited in naive factorization, since the emission diagram with a tensor meson produced from vacuum is vanished. While contributions from the so-called hard scattering emission diagrams and annihilation type diagrams are important and calculable in the perturbative QCD approach. The branching ratios of most decays are in the range of \(10^{-4}\) – \(10^{-8}\) , which are bigger by 1 or 2 orders of magnitude than the predictions given by the naive factorization, but consistent with the predictions from the QCD factorization and the recent experimental measurements. We also give the predictions for the direct \(CP\) asymmetries, some of which are large enough for the future experiments to measure. We also find that, even with a small mixing angle, the mixing between \(f_2\) and \(f_2^{\prime }\) can bring remarkable changes to both branching ratios and the direct \(CP\) asymmetries for some decays involving \(f_2^{(\prime )}\) mesons. For decays with a vector meson and a tensor meson in final states, we predict a large percentage of transverse polarization contributions due to the contributions of the orbital angular momentum of the tensor mesons.     

A dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express

The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120 km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft and ground-based observations of infrared emission from CO2, O2 and NO have established that photochemical and dynamic activity controls the structure of the upper atmosphere of Venus. These data, however, have left unresolved the precise altitude of the emission owing to a lack of data and of an adequate observing geometry. Here we report measurements of day-side CO2 non-local thermodynamic equilibrium emission at 4.3 microm, extending from 90 to 120 km altitude, and of night-side O2 emission extending from 95 to 100 km. The CO2 emission peak occurs at approximately 115 km and varies with solar zenith angle over a range of approximately 10 km. This confirms previous modelling, and permits the beginning of a systematic study of the variability of the emission. The O2 peak emission happens at 96 km +/- 1 km, which is consistent with three-body recombination of oxygen atoms transported from the day side by a global thermospheric sub-solar to anti-solar circulation, as previously predicted.     

The loss of ions from Venus through the plasma wake

Venus, unlike Earth, is an extremely dry planet although both began with similar masses, distances from the Sun, and presumably water inventories. The high deuterium-to-hydrogen ratio in the venusian atmosphere relative to Earth's also indicates that the atmosphere has undergone significantly different evolution over the age of the Solar System. Present-day thermal escape is low for all atmospheric species. However, hydrogen can escape by means of collisions with hot atoms from ionospheric photochemistry, and although the bulk of O and O2 are gravitationally bound, heavy ions have been observed to escape through interaction with the solar wind. Nevertheless, their relative rates of escape, spatial distribution, and composition could not be determined from these previous measurements. Here we report Venus Express measurements showing that the dominant escaping ions are O+, He+ and H+. The escaping ions leave Venus through the plasma sheet (a central portion of the plasma wake) and in a boundary layer of the induced magnetosphere. The escape rate ratios are Q(H+)/Q(O+) = 1.9; Q(He+)/Q(O+) = 0.07. The first of these implies that the escape of H+ and O+, together with the estimated escape of neutral hydrogen and oxygen, currently takes place near the stoichometric ratio corresponding to water.     

2-正n边形的旋转排列计数的轮换指标计算

对正n边形旋转排列计数进行了推广,对3类条件下的2正n边形在两类变换下的轮换指标进行了研究,得到了对应的计算公式以及其轮换指标。     

棱镜转动定理

棱镜成像是静态问题，转动棱镜的成像方位变化属动态问题。反射棱镜绕某轴旋转，其特征方向就绕同一根轴转至新的方位，利用与的简单关系，比较特征方向处于新、旧两种方位时的棱镜成像，同时得到了棱镜调整计算的显式简单公式和“棱镜转动定理”。     

轮换对称多项式通式的构造及初等轮换式的自动发现

通过改进算法的轮换对称多项式的通式构造程序,研究了初等轮换对称多项式的构造,编写Maple程序得到了3元到7元的初等轮换对称多项式;提出并编程实现列表乘法运算,为较多元多项式的线性表示及多项式的通式构造提供了强有力的工具;提出了3个猜想并编程实现部分验证.     

最后进近飞行中的误差分析

通过引入模型分析研究了最后进近目视精度大小,通过结合最后进近的飞行参数和飞行方法,得出最后进近误差最小值的一个范围,对于实际飞行有重要的参考意义。     

美神-爱神-复仇神--解读《伊尔的美神》

梅里美的小说有一个共同主题，即高扬人的自然本性中的真善美，极力鞭笞文明社会造成的人性的堕落。短篇小说《伊尔的美神》也同样表现了梅里美对最自然的生命力的礼赞以及对最真纯的人性的渴求。梅里美并没有鲜明地标举自己的创作意图，而是把它隐含在叙述者“我”言行不一和变化多端的性格之中。贯穿全篇的女神意象，集美神、爱神、复仇神三位于一体，既是原始生命力的象征性的表现，又是对现代文明中受损毁的人性的有力批判和强烈反抗，使作品具有了神话层面的深层隐喻。     

The runaway greenhouse and the accumulation of CO2 in the Venus atmosphere

Conditions on Earth would be as hostile as on Venus if the Earth were closer to the Sun by only 6-10 million miles.     

三个几何不等式的证明

应用三角形重心坐标和三元二次型不等式,建立涉及三角形内部一动点的三个新型的几何不等式。     

科学新闻与占星辨谬——1874年金星凌日观测活动的中文记载

金星凌日的观测在天文学史上有着极其重要的意义,它直接与日地距离的测定有着密切的关系.1874年的金星凌日主要在中国等东半球某些地区可见,西方多个国家曾派遣天文学家到中国进行观测.整理并简要分析了这次金星凌日发生前后的预告、观测以及民间星占言论的相关史料.     

最终要约仲裁研究

针对当前最终要约仲裁领域中的不足和缺点，提出了一套完整而简单适用的方法，旨在诱导仲裁人和冲突者的行为，着重讨论了在不完全信息下，冲突者的可行措施集的生成，仲裁人如何制定仲裁理想解和冲突者如何制定意向解的过程，以及仲裁人选择仲裁解的过程。最后，对一个最终要约仲裁案例进行了分析。