Carbon compounds in Apollo 11 lunar samples

Are they entrapped solar wind particles, meteoritic or cometary contributions, remnants of a primordial atmosphere or products of the degassing of the Moon ?     

Active optical clock

This article presents the principles and techniques of active optical clock, a special laser combining the laser physics of one-atom laser, bad-cavity gas laser, super-cavity stabilized laser and optical atomic clock together. As a simple example, an active optical clock based on thermal strontium atomic beam shows a quantum-limited linewidth of 0.51 Hz, which is insensitive to laser cavity-length noise, and may surpass the recorded narrowest 6.7 Hz of Hg ion optical clock and 1.5 Hz of very recent optical lattice clock. The estimated 0.1 Hz one-second instability and 0.27 Hz uncertainty are limited only by the relativistic Doppler effect, and can be improved by cold atoms. Supported by the National Basic Research Program of China (Grant No. 2005CB724500) and National Natural Science Foundation of China (Grant No. 10874009     

An optical lattice clock

The precision measurement of time and frequency is a prerequisite not only for fundamental science but also for technologies that support broadband communication networks and navigation with global positioning systems (GPS). The SI second is currently realized by the microwave transition of Cs atoms with a fractional uncertainty of 10(-15) (ref. 1). Thanks to the optical frequency comb technique, which established a coherent link between optical and radio frequencies, optical clocks have attracted increasing interest as regards future atomic clocks with superior precision. To date, single trapped ions and ultracold neutral atoms in free fall have shown record high performance that is approaching that of the best Cs fountain clocks. Here we report a different approach, in which atoms trapped in an optical lattice serve as quantum references. The 'optical lattice clock' demonstrates a linewidth one order of magnitude narrower than that observed for neutral-atom optical clocks, and its stability is better than that of single-ion clocks. The transition frequency for the Sr lattice clock is 429,228,004,229,952(15) Hz, as determined by an optical frequency comb referenced to the SI second.     

在B-LSSM中Higgs质量的理论修正

在具有局部B-L规范对称性的最小超对称模型扩展(B-LSSM)中,通过有效位势方法,对Higgs粒子质量进行了单圈辐射修正和数值分析.依据Higgs粒子理论质量和实验数据,对B-LSSM的相关参数进一步地限制,约束参数空间,从而使B-LSSM的参数空间更加完善.     

重夸克偶素的高阶变分微扰修正

设置含有变分参数的母哈密顿量作为零级哈密顿量,选择该母哈密顿量的精确解作为试探波函,对重夸克偶素基态利用基于积分方程的改进的变分微扰论,得到了只有几项的高阶修正波函数和高阶能量修正．它表明这种方法不仅可提高计算结果的精度而且可确保微扰级数的收敛性,我们的计算结果更接近精确值,修正波函数的收敛性得到改善．