二维J1-J2模型中四量子比特的热纠缠特性

我们研究了二维.J1-J2模型中三种四量子比特的热纠缠特性,结果发现,临界温度基本上随挫变参量α的增大而减小.我们也发现,通过选择合适的挫变参量α可以制备最大纠缠态.     

GCP Code and Analysis of J/ψ Suppression in p-A and A-A Collisions

Using the General Cascade Program (GCP), the production and absorption of J/ψ,in p-A and A-A collisions have been studied. Nucleon absorption mechanism and comoverabsorption mechanism are considered to investigate the J/ψ suppression. The results agreewell with experimental data of J/ψ production, escept for the data in Pb-Pb collision.     

Coherent scattering diagnostic method on heating waves in J.E.T.

The application of a large angle microwave scattering diagnostic to the J.E.T. plasma in order to detect the penetration of the Lower Hybrid heating waves is examined. Fun damental equations of the coherent scattering are briefly reviewed and the scattered power is described on the basis of a full electromagnetic warm plasma dispersion relation. The choice of the best suited incident wavelength and its consequences on the performances of the scattering experiment (range of measurable n, refraction effects, spatial resolution, etc.) are considered. The feasibility of such an experiment with the existing sources and technology is also considered.     

Resolved Photoproduction of J/ψ at HERA

The J/ψ photoproduction via resolved photon process at HERA is studied. It turns out that the J/ψ production is dominated by the leading order production process in low pt range (p_t < 4 GeV), while in the high pt range (p_t > 4 GeV), it is dominated by the fragmentation processes. The difference of J/ψ cross section caused by using GRV and DO photon structure functions is large, especially in the large negative rapidity range. Hence it is possible to use the J/ψ photoproduction process to probe the parton distribution of photon and proton, as well as to test the gluon and heavy quark fragmentation of J/ψ from the perturbative QCD.     

Comment on “The properties of free polymer surfaces and their influence on the glass transition temperature of thin polystyrene films” by J.S. Sharp,J.H. Teichroeb and J.A. Forrest

Sharp, Teichroeb and Forrest [J.S. Sharp, J.H. Teichroeb, J.A. Forrest, Eur. Phys. J. E 15, 473 (2004)] recently published a viscoelastic contact mechanics analysis of the embedment of gold nanospheres into a polystyrene (PS) surface. In the present comment, we investigate the viscoelastic response of the surface and conclude that the embedment experiments do not support the hypothesis of a liquid surface layer of sufficiently reduced “rheological temperature” to explain reports of very large reductions in the glass temperature of freely standing ultrathin polystyrene films. We also report some errors and discrepancies in the paper under comment that resulted in an inability to reproduce the reported calculations. We present our findings of error in a spirit of clarifying the problem of embedment of spheres into surfaces and in order that others can understand why they may not reproduce the results reported by Sharp, Teichroeb and Forrest. In the comment, we also examine the effects of the magnitude of the forces that result from the polymer surface-nanosphere particle interactions on the viscoelastic properties deduced from the embedment data and we provide a comparison of apparent surface or “rheological” temperature vs. experimental temperature that indicates further work needs to be performed to fully understand the surface embedment experiments. Finally, we comment that the nanosphere embedment measurements have potential as a powerful tool to determine surface viscoelastic properties.     

Chaotic Motion of the cc System and a New Mechanism of J/Ø Suppression

Based on random matrix theory and reduced BS equation, it is found that the regular motion of cc system can be expected at a small value of color screening mass but the chaotic motion at a large one. It is shown that the level mixing due to color screening serves as a new mechanism resulting in J/Ø suppression. Moreover, this kind of suppression can occur before the color screening mass reaches its critical value for J/Ø dissociation. In addition, it is. implied that a strong J/Ø suppression is possible in the absence of dissociation of J/Ø.     

赫兹对阴极射线的实验研究及其重要影响

根据赫兹的日记、书信、文集及相关文献,对赫兹所进行的阴极射线的实验研究工作进行了仔细考察,指出他对阴极射线的一系列实验研究为揭示阴极射线的全部特性奠定了重要基础,对勒纳德和汤姆孙在这一领域的研究产生了直接影响．     

Study of the rare decay J/ψ→e~+e~-φ

We study the decay process of J/ψ→e~+e~-φ where the relatively clean electromagnetic(EM) transitions appear at leading order at tree level while the hadronic contributions only emerge via hadronic loop transitions. We include the low-lying scalar f_0(980) and pseudoscalar η/η as the dominant contributions in the evaluation of the hadronic loop contributions. It is found that the hadronic effects are negligible compared with the EM contributions.The decay width of J/ψ→e~+e~-φ is determined to be about 2.12 × 10~(-6) ke V if there is no other leading mechanism contributing. This result will be tested by the BESIII experiment with a large J/ψ data sample.     

选择性激发技术在偶合常数精确测量中的应用

采用基于简单Gaussian软脉冲的选择性激发技术来获得自旋系统的一维反相磁化分裂峰,并结合J-Doubling方法来精确测量该分裂峰的J偶合常数,对于重叠分裂峰或者线宽大、偶合分裂小的谱峰的J偶合常数的精确测量,该方法尤其适合.     

Search for ψ(4S) → ηJ/ψ in B~±→ ηJ/ψK~± and e~+e~-→ ηJ/ψ processes

We search for the ψ(4S) state in the B~±→ηJ/ψK~± and e~+e~-→ηJ/ψ processes based on the Belle measurements with the assumed mass M =(4230±8) MeV/c~2 and width Γ =(38±12) MeV. No significant signal is observed in the ηJ/ψ mass spectra. The 90% confidence level upper limit on the product branching fraction B(B~±→ψ(4S)K~±)B(ψ(4S)→ηJ/ψ) 6.8×10~(-6) is obtained in the B~±→ηJ/ψK~± decays. By assuming the partial width of ψ(4S)→e~+e~-to be 0.63 ke V, a branching fraction limitB(ψ(4S)→ηJ/ψ) 1.3% is obtained at the 90%confidence level in e~+e~-→ηJ/ψ, which is consistent with the theoretical prediction.     

Concentrations and velocity distributions of positive ions in laser ablation of copper

It is shown that the generation of secondary electrons by excited neutrals hitting a surface makes the so-called probe method unsuited for measuring the positive ion fraction in laser ablation plumes. Experiments have been performed in a modified set-up, in which the disturbance by secondary electrons is avoided. For a typical case of Cu irradiated in ultra-high vacuum by nanosecond excimer laser pulses of 3 J cm^–2 the ionized fraction is about 10^–8 at a distance of 60 cm. This number is in fair agreement with Saha-Langmuir predictions based on the assumption of local thermal equilibrium at an estimated temperature of about 3000K. Angular-resolved time-of-flight measurements show that there are three different ion velocity distributions. A slow contribution (kinetic energy 2eV) with an angular distribution peaked along the normal, and two fast, isotropic contributions (kinetic energy 20–50 eV). The fast contributions are attributed to ions involved in a Coulomb explosion.     

The individual success of musicians, like that of physicists, follows a stretched exponential distribution by J.A. Davies

Comment on Eur. Phys. J. B 27, 445 (2002) We analyze the distribution of success of musicians, comparing a stretched exponential (found by J.A. Davies [Eur. Phys. J. B 27, 445 (2002)]) with a distribution of the family of the q-exponential (presenting an intermediate power-law regime with a crossover to an exponential tail). We find that both assumptions yield comparable results, within the available range of data, hence a definite conclusion cannot yet be taken. But this example joins many others that has been found to be fairly described by q-exponentials (or variations of it), which may be indicative that there is a (significantly large) class of systems described by nonextensive statistical mechanics, from where q-exponentials naturally appear. Received 17 October 2002 Published online 31 December 2002     

共振拉曼光谱研究卟啉二酸H_4~(2+)TSPP的J-聚焦

用共振拉曼光谱和ＵＶ Ｖｉｓ吸收光谱考察了离子强度对四一（对一磺酸基）苯基卟啉二酸（Ｈ２＋４ＴＳＰＰ）Ｊ 聚集体形成的影响。实验表明加入少量的ＮａＣｌＯ４有助于聚集体的形成,而Ｎａ ＣｌＯ４的浓度过高则倾向于形成单体。ＮａＣｌＯ４的加入不改变聚集体中分子的构型和排列方式,但高浓度的ＮａＣｌＯ４可能在聚集体中引入某种缺陷,使激子态发生局域化。我们还得到了具有宏观尺寸的纤维状Ｈ２＋４ＴＳＰＰ沉淀,并研究了其固体显微拉曼谱。     

The moment of inertia of the proto neutron star PSR J0348+0432 under neutrino trapped

The moment of inertia of the proto neutron star PSR J0348+0432 is studied in the framework of relativistic mean field theory under neutrino trapped. We find that the temperature of the PNS PSR J0348+0432 increases with the increase of the baryon number density and at the center of the star it is in the range T_c = 41.662–45.685 MeV. Corresponding to the observation mass 1.97–2.05 M_⊙, the radius of the NS PSR J0348+0432 is in the range 12.948–12.16 km whereas that of the PNS PSR J0348+0432 is in the range 14.46–13.561 km. The radius of the PNS PSR J0348+0432 has increased by 11.7%–11.5% compared with that of the NS PSR J0348+0432. The central moment of inertia of the PNS PSR J0348+0432 is in the range 2.207?×?10⁴⁵–1.914?×?10⁴⁵ g cm² whereas that of the NS PSR J0348+0432 is only in the range 1.9?×?10⁴⁵–1.552?×?10⁴⁵ g cm². Compared with the moment of inertia of the NS PSR J0348+0432, the central moment of inertia of the PNS PSR J0348+0432 increases by 16%–23%.     

通过J/Ψ→N(N-)M衰变研究N*时的核子极点效应

研究了J／Ψ→pp^-π衰变过程中核子极点图的贡献，特别是由离壳效应带来的贡献．发现衰变宽度对形状因子是敏感的．在通过用J／Ψ→pp^-π衰变研究N^*时，核子极点图作为背景道的贡献是非常重要的；在通过J／Ψ→pp^-η和pp^-η研究N^*时，核子极点图的贡献可忽略不计；在通过J／Ψ→pp^-ω研究N^*时，核子极点图有明显的贡献．     

A Study on the Search for 1-+ Exotic Hybrid in J/Ø Decay Process

The suggestion on the search for 1^-+ exotic hybrid in a particular J/Ø decay process has been presented. We give the moment expressions for the cases of the boson resonance X with various spin-parity JXC produced in this J/Ø decay process in terms of the generalized moment analysis method. The result shows that using these moments we can identify the 1^-+ exotic hybrid produced in this kind of J/Ø decay process except for some special cases.     

Physics with high energy electron-positron colliding beams with the MARK J detector

This report reviews the experimental investigation of high energy e⁺e^? interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the on-line data collection and the off-line analysis are also outlined. Results are presented on tests of quantum electrodynamics using e⁺e^? → e⁺e^?, μ⁺μ^? and τ⁺τ^?, on the measurement of R, the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant α_s.     

Pseudoscalar mixing in J/ψ and ψ(2S)decay

Based on the branching fractions of J/ψ(ψ(2S))→ VP from different collaborations, pseudoscalar mixing is extensively discussed with a well established phenomenological model. The mixing angle is determined to be -14° by fitting to the new world average if only quark content is considered. After taking into account the gluonic content in η and η' simultaneously, the investigation shows that η favors only consisting of light quarks, while the gluonic content of η' is Z2η', = 0.30±0.24.     

Interference of probabilities and number field structure of quantum models

We study the probabilistic consequences of the choice of the basic number field in the quantum formalism. We demonstrate that by choosing a number field for a linear space representation of quantum model it is possible to describe various interference phenomena. We analyse interference of probabilistic alternatives induced by real, complex, hyperbolic (Clifford) and p‐adic representations.     

Verification of the optimal probabilistic basis of aural processing in pitch of complex tones

Periodicity pitch for complex tones has been quantitatively accounted for by a two-stage process of Fourier-frequency analysis subject to random errors and significant nonlinearities, followed by an harmonic pattern recognizer that makes an optimum probabilistic estimate of the fundamental period of musical and speech sounds. The theory predicts that periodicity pitch is a multimodal probabilistic function of a given stimulus. A clear and empirically supported distinction is made between limitations on the pitch mechanism caused by the stochastic nature of aural frequency representation and by the deterministic resolution bandwidths of aural frequency analysis. This model was developed earlier [J. L. Goldstein, J. Acoust. Soc. Am 54, 1496-1516 (1973)] to account for probabilistic data on pitch errors [A. J. M. Houtsma and J. L. Goldstein, J. Acoust. Soc. Am. 51, 520 (1972)] measured with periodic stimuli comprising two successive harmonics. This paper presents new predictions by the theory that were calculated, with computer simulation where needed, for known probabilistic pitch data from stimuli comprising three to six successive harmonics. Predicted pitch errors increase with increasing errors in estimating the frequencies of stimulus harmonics and decrease as more harmonics are added to the stimulus. Optimum processor theory fully accounts for the multicomponent pitch data on the basis of similar errors in estimating component stimulus frequencies as reported earlier, thus providing further evidence for the optimum probabilistic basis of aural signal processing in pitch of complex tones.