Search for supersymmetry at LEP-2

An extensive effort to search for a hint of a supersymmetric signal was carried out by the four LEP Collaborations. All LEP data, up to centre-of-mass energy of 209 GeV, was carefully analysed with no observed SUSY signal. In an attempt to further increase the sensitivity of the search, the four groups combined some of their searches, to no avail.     

Development of the Monte Carlo model CASCADE-2004 of high-energy nuclear interactions

The Monte Carlo code CASCADE for the calculation of inelastic hadron- and nucleus-nucleus interactions at energies from several tens of MeV up to several tens of GeV and for modelling of nuclear-physical processes accompanying the transport of particles and nuclei in matter is improved by considering a more detailed model of decay of highly excited residual (after-intranuclear-cascade) nuclei. Results of calculations are in good agreement with experiment. However, there are some deviations for light-isotope production, which prompt the necessity of developing more correct models of evaporation and strong asymmetric high-energy fission.     

Particle systems with variable length

We present a new class of one-dimensional particle systems, in which the number of components may change in the process of interaction. We suggest that some of these systems display spontaneous symmetry breaking. Received: 16 August 2002     

Effective Hamiltonian for scalar theories in the Gaussian approximation

We use a Gaussian wave functional for the ground state to reorder the Hamiltonian into a free part with a variationally determined mass and the rest. Once spontaneous symmetry breaking is taken into account, the residual Hamiltonian can, in principle, be treated perturbatively. In this scheme we analyze the O(1) and O(2) scalar models. For the O(2)-theory we first explicitly calculate the massless Goldstone excitation and then show that the one-loop corrections of the effective Hamiltonian do not generate a mass.     

On the Bethe ansatz for random directed polymers

We show that the inclusion of the (gapless) center-of-mass motion together with a functional integral representation of the Bethe wave function allows one to predict exactly the critical exponents for random directed polymers in (1+1) dimensions. The corresponding amplitudes are computed; they compare satisfactorily with existing numerical data. Within a replica-symmetric theory, we find that the Green function of the polymer has the form recently proposed by Parisi.     

转镜式高速扫描相机时间分辨率的测定

 介绍了产生时间分辨率的原因，测量时间分辨率在高速摄影中的作用，前人曾做过的工作，时间分辨率测定的难点；着重介绍了新的测量方法，给出了实际测定的结果。结果表明，对于GSJ型相机，时间分辨率可达8.6 ns，测量的均方根误差为1.1 ns。     

纳米材料二氧化锡的制备和激子态光学特性研究

报道纳米材料二氧化锡的制备和室温下激子态光学特征，应用弱量子限域下激子响应模型对结果进行了解释。     

Symmetry breaking and measurement theory

For studying the problem of measurement we accept the statistical interpretation of quantum mechanics, but we take into account, that in a sequence of measurements, offdiagonal terms arise which cannot obviously be interpreted as the probability of a sequence of macroscopic events. We demonstrate, however, their vanishing for ordinary measurement processes by observing that the measurement apparatus undergoes a symmetry breaking transition during the measurement.1. On leave from the Central Research Institute for Physics, Budapest, Hungary.     

Electrical transport and high pressure studies on bulk Ge20Te80 glass

The electrical resistivity of bulk Ge₂₀Te₈₀ has been measured as a function of pressure and temperature. At 5 GPa, an amorphous semiconductor-to-crystalline metal transition has been observed. The sample recovered from the high pressure cell, after the application of 7 GPa, has a face-centred cubic structure with a lattice constant of 6·42 A. In crystalline sample, the semiconductor-to-metal transition occurs at 7 GPa. The thermoelectric power has also been measured for glassy samples in the temperature range 300–240 K.     

交联1，4－顺式聚丁二烯的取向结晶

用ＷＡＸＤ和ＳＡＸＳ研究交联１，４－顺式聚丁二烯的取向结晶．结果表明：该试样在拉伸状态时，形成折叠链片晶，而不是伸直链纤维晶．片晶之间不断产生新的片晶，使长周期减小，并且片晶的横向尺寸不断增大，由此导致结晶度增大．