A Simple Singlet Fermionic Dark-Matter Model Revisited

We evaluate the spin-independent elastic dark matter-nucleon scattering cross section in the framework of the simple singlet fermionic dark matter extension of the standard model and constrain the model parameter space with the following considerations:(i)new dark matter measurement,in which,apart from WMAP and CDMS,the results from the XENON experiment are also used in constraining the model;(ii)new fitted value of the quark fractions in nucleons,in which the updated value of fta from the recent lattice simulation is much smaller than the previous one and may reduce the scattering rate significantly;(iii)new dark matter annihilation channels,in which the scenario where top quark and Higgs pairs produced by dark matter annihilation was not included in the previous works.We find that unlike in the minimal supersymmetric standard model,the cross section is just reduced by a factor of about 1/4 and dark matter lighter than 100 GeV is not favored by the WMAP,CDMS and XENON experiments.

Single W Boson Production at s=189 GeV

Single W boson production is analyzed in a data sample collected by L3 detector at Large Electron Positron Collider in 1998.The integrated luminosity is 176.4pb^(-1)with center-of-mass energy at√s=189GeV.The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets.The total cross section of single W production is measured to be 0.58±0.13±0.04 pb,in good agreement with standard model prediction.From this measurement,the limits on the anomalousγWW triple-gauge-boson couplings are derived at 95%confidence level:-0.48<△_(kr)<0.38 and-0.50<λ_(γ)<0.41.

Extraction of the Structure Functions in τ→3πv Decay Using Li Model

The structure functions in theτ→3πv decay are extracted using the model proposed by Li.The predictions of Li model are compared with KS ones and the data from OPAL experiment.It is found that predictions by the model forωA(Q2)are consistent with the data except for in the high energy region(Q2>1.2 GeV2),andωC,ωD,ωE normalized toωA are in reasonable agreement with the experimental results.Correction factors to the Breit-Wigner distribution of a1 and the Lagrangian of this decay are proposed to the model.

基于标准平面镜的双目偏折术系统标定

相位偏折术中,系统标定精度对面形测量精度具有决定性的影响。采用带标记点标靶进行标定时,由于其表面不是理想平面而引入误差,导致虚像姿态求解不精确,进而影响标定精度。通过使用高精度的标准平面镜作为反射镜,从初始系统参数开始,采用交替方向优化的方法实现系统几何参数的标定,提高了标定精度,同时避免了变量过多导致的矩阵病态问题。使用该方法对双目相位测量偏折系统进行标定后,对100 mm口径的标准平面镜进行了对比测量。由测量面形可知,该方法可显著降低测量均方根误差和低频面形误差。相比于传统带标记点标靶的方法,有效提高了标定的精度和稳定性。