Doubly-charged scalar in four-body decays of neutral flavored mesons

We study the four-body decays of neutral flavored mesons,including■,and■.These processes,which could be induced by a hypothetical doubly-charged scalar particle,do not conserve the lepton number.Assuming,as an example,that the mass of the doubly-charged particle is 1000 Ge V,and using the upper bounds of the couplings,we calculate the branching ratios of different channels.For■,and,it is of the order of 10~(-30),10~(-32)–10~(-29),and 10~(-33)–10~(-28),respectively.Based on the experimental results for the■channels,we also find the upper limit for the quantity■     

强激光场中氢负离子双光子电离能量谱的研究

利用强场近似(Strong field approximation,SFA)方法研究氢负离子(H-)在强激光场中双光子电离的能量谱,所得到的电离谱随角度的变化规律与实验结果符合得很好.进一步的研究表明,H-离子在强激光场中双光子电离的能量谱与有质动力能有关.激光场强度越大,光电子的有质动力能也越大,能量谱向左移动越明显...     

Frequency-modulated excitation of Rydberg potassium atoms by using B-spline

By using the B-spline expansion technique and a model potential of the alkali atoms, the properties of frequency- modulated excitation of Rydberg potassium atoms in a static electric field and a microwave field are investigated by using the time-dependent two-level approach. We successfully reproduce the square wave oscillations in the low frequency, the stair step population oscillations in the intermediate frequency, and the multiphoton transitions in the high frequency with respect to the unmodulated Rabi frequency, which have been observed experimentally by Noel et al. [Phys. Rev. A 58 2265 (1998)]. Furthermore, we also numerically obtain the discretized Rabi oscillations predicted in the Landau-Zener accumulation model.     

Bs Semileptonic Decays to Ds and D^＊8 in Bethe-Salpeter Method

Using the relativistic Bethe-Salpeter method, the electron energy spectrum and the semileptonic decay widths of B^0 → Ds^- e＋ve and B^0 → Ds^＊-e＋ve are calculated. We obtain a large branching fraction Br（Bs → Dseve） = （2.85 ± 0.35）% and Br（Bs→ D^＊s eue） = （7.09 ±0.88）%, which can be easily detected in future experiments.     

Optimization of Single or Range of Harmonics by Using Two Gas Jets

The interference of high-order harmonics generated by two successive gas jets within a single laser pulse is discussed by a modeling with the inclusion of macroscopic propagation of the fundamental and harmonic fields in an ionizing medium. Based on the interference, we show that one can extract the laser Rayleigh range from the interference of harmonics and the accuracy of retrieve is independent of carrier-envelope phase while dependent on the pulse duration. Moreover~ we demonstrate that it is possible to optimize the single or range of harmonics with a high ratio relative to the adjacent orders by changing the separation of two gas jets, which is unavailable by using a single gas jet and linear polarized laser pulse.     

利用两色红外组合场驱动氦原子产生单个阿秒脉冲

利用数值求解原子在强激光场中的含时薛定谔方程,对一维氦原子处于两色红外组合场中产生的高次谐波进行了研究,研究发现,在组合场驱动下,谐波谱的截止位置可以拓展到 ,从而得到脉宽较短的多个阿秒脉冲,通过改变两束激光的相位延迟,最终得到了33.8as的单个脉冲。进一步利用小波变换分析了阿秒脉冲的发射特征,发现单个阿秒脉冲实现是对电子长路径抑制的结果.     

优化两色组合场参数获得单个阿秒脉冲

基于经典方法优化了组合场中基频场和低频场的强度比,利用优化后的组合场驱动一维氦原子,通过求解含时薛定谔方程研究了氦原子产生的高次谐波,其截止位置得到扩展,再考虑基频场初相位对产生高次谐波的影响,能够得到脉宽为37as的单个阿秒脉冲.     

用伪谱方法计算强激光场中一维原子的阈上电离谱

引入非线性空间变换,用伪谱方法求解了一维原子在强激光场中的薛定谔方程,再利用B样条函数和傅立叶级数的线性组合构造原子未微扰的本征函数,计算了一维原子在强激光场中的阈上电离谱,其结果与分裂算符法得到的结果符合得很好.     

极化门控制下中红外激光场驱动He原子产生的单个阿秒脉冲

由中红外激光场(波长为2128nm)驱动He原子,在极化门的控制下,通过强场近似方法(SFA)研究了He原子发射高次谐波的特点.研究表明,在这种组合场驱动下He原子可产生截止位置很高的高次谐波,并且在接近截止位置的平台区展现了超连续的特点,对该超连续部分的高次谐波进行叠加,可得到宽度为44.5as的单个超短脉冲.为了了解该超短阿秒脉冲的产生机理,我们对高次谐波谱的发射过程进行了时频分析,分析表明由于极化门的存在,有效地抑制了极化门以外的阿秒脉冲的发射,从而获得单个阿秒脉冲.     

优化两色组合场参数获得单个阿秒脉冲

基于经典方法优化了组合场中基频场和低频场的强度比,利用优化后的组合场驱动一维氦原子,通过求解含时薛定谔方程研究了氦原子产生的高次谐波,其截止位置得到扩展,再考虑基频场初相位对产生高次谐波的影响,能够得到脉宽为37as的单个阿秒脉冲.