Phase space and multihadron production in annihilation processes at present energies

With the conjecture that the weak neutral current should have equal status in symmetry as the other weak and electromagnetic currents, we determine it to be a pure axial-vector. This means that the weak interaction of the neutral current is parity conserving. The fundamental interactions of leptons thereby complete the whole scheme of (1 + γ₅)/2, (1 ? γ₅)/2,1 and γ₅.     

Stochastic processes and multihadron production

Acta physica Academiae Scientiarum Hungaricae - Statistical multihadron production models are considered in a stochastic framework. The predictions of the stochastic quark model of hadron clusters...     

Passive scalar intermittency in low temperature helium flows

We report new measurements of mixing of passive temperature field in a turbulent flow. The use of low temperature helium gas allows us to span a range of microscale Reynolds number, R(lambda), from 100 to 650. The exponents xi(n) of the temperature structure functions approximately r(xi(n)) are shown to saturate to xi(infinity) approximately 1.45+/-0.1 for the highest orders, n approximately 10. This saturation is a signature of statistics dominated by frontlike structures, the cliffs. Statistics of the cliffs' characteristics are performed, particularly their widths are shown to scale as the Kolmogorov length scale.     

Solar flare intermittency and the earth's temperature anomalies

We argue that Earth's short-term temperature anomalies and the solar flare intermittency are linked. The analysis is based upon the study of the scaling of both the spreading and the entropy of the diffusion generated by the fluctuations of the temperature time series. The joint use of these two methods evidences the presence of a Lévy component in the temporal persistence of the temperature data sets that corresponds to the one that would be induced by the solar flare intermittency. The mean monthly temperature data sets cover the period from 1856 to 2002.     

Klein-Gordon equations for energy-momentum of the relativistic particle in rapidity space

The notion of four-rapidity is defined as a four-vector with one time-like and three space-like coordinates. It is proved, the energy and momentum defined in the space of four-rapidity obey Klein-Gordon equations constrained by the classical trajectory of a relativistic particle. It is shown, for small values of a proper mass influence of the constraint is weakened and the classical motion gains features of a wave motion.     

Relating multihadron production in hadronic and nuclear collisions

The energy-dependence of charged particle mean multiplicity and pseudorapidity density at midrapidity measured in nucleus–nucleus and (anti)proton–proton collisions are studied in the entire available energy range. The study is performed using a model, which considers the multiparticle production process according to the dissipating energy of the participants and their types, namely a combination of the constituent quark picture together with Landau relativistic hydrodynamics. The model reveals interrelations between the variables under study measured in nucleus–nucleus and nucleon–nucleon collisions. Measurements in nuclear reactions are shown to be well reproduced by the measurements in pp/[`(p)]p{\bar{\mathrm{p}}}{\mathrm{p}} interactions and the corresponding fits are presented. Different observations in other types of collisions are discussed in the framework of the proposed model. Predictions are made for measurements at the forthcoming LHC energies.     

Diffusion-controlled electron transfer processes and power-law statistics of fluorescence intermittency of nanoparticles

A mechanism involving diffusion-controlled electron transfer processes in Debye and non-Debye dielectric media is proposed to elucidate the power-law distribution for the lifetime of a blinking quantum dot. This model leads to two complementary regimes of power law with a sum of the exponents equal to 2, and to a specific value for the exponent in terms of a distribution of the diffusion correlation times. It also links the exponential bending tail with energetic and kinetic parameters.     

Fractality and degree correlations in scale-free networks

Fractal scale-free networks are empirically known to exhibit disassortative degree mixing. It is, however, not obvious whether a negative degree correlation between nearest neighbor nodes makes a scale-free network fractal. Here we examine the possibility that disassortativity in complex networks is the origin of fractality. To this end, maximally disassortative (MD) networks are prepared by rewiring edges while keeping the degree sequence of an initial uncorrelated scale-free network. We show that there are many MD networks with different topologies if the degree sequence is the same with that of the (u,v)-flower but most of them are not fractal. These results demonstrate that disassortativity does not cause the fractal property of networks. In addition, we suggest that fractality of scale-free networks requires a long-range repulsive correlation, in the sense of the shortest path distance, in similar degrees.     

Effect of secondary processes on material hardening under low temperature radiation

Evolution of radiation barrier (vacancies and interstitials) clusters is analyzed under low temperature radiation in the presence of the most important secondary effects: recombination and formation of divacancy complexes. It is proposed a barrier hardening model in that mechanisms of mutual annihilation of the vacancy and interstitial barriers and their clusterization play a main role. It is taken into account reducing barrier densities due to barrier mutual annihilation of two different types and developing the large clusters by interconnection of two barriers of the same type.     

Ionization transients of shallow levels in silicon space charge layer at low temperature

In silicon diodes, at cryogenic temperatures, transient currents due to the depletion layer formation are not monotonic in time, but present a peak. It is shown that, taking appropriate experimental cares, these transient currents are accurately described by a theoretical model based on Frenkel-Poole effect. Particularly, the influence of compensation, through its bulk resistivity effect, is discussed. Both n and p-type silicon diodes are shown to exhibit the same features, contrary to some author's assertion.     

低温下封闭空间内部氢的相变相平衡特性研究

为了研究低温下封闭空间内工质的相变相平衡特性过程,利用Fluent建立了薄壁微小球体的封闭空间二维模型,对该球体的相变相平衡过程进行传热传质数值仿真。获得了球体内部的温度场及相体积分数分布随时间变化的规律,发现在相变相平衡过程中,球体内外温差逐渐减小并趋于不变,能为相变提供冷量,使得液相的量近似呈线性增加;并且球体材料的热物性当中比热容对相变过程的影响最大,而热导率几乎无影响。     

低温材料及低温钻杆的研发现状

随着目前深井和超深井的发展,以及北方、西北地区高寒地带油气井的开发,越来越多的钻杆要求具有抵抗低温或者超低温度的性能需要.低温钻杆成为目前极有发展前景的石油工业技术之一.文中在综述低温材料研究现状的基础上,阐述了低温材料钻杆的工艺现状及其发展趋势.     

Numerical simulations of strong-field processes in momentum space

The time-dependent Schrodinger equation(TDSE) is usually treated in the real space in the textbook.However,it makes the numerical simulations of strong-field processes difficult due to the wide dispersion and fast oscillation of the electron wave packets under the interaction of intense laser fields.Here we demonstrate that the TDSE can be efficiently solved in the momentum space.The high-order harmonic generation and above-threshold ionization spectra obtained by numerical solutions of TDSE in momentum space agree well with previous studies in real space,but significantly reducing the computation cost.     

Exclusive processes in position space and the pion distribution amplitude

We suggest to carry out lattice calculations of current correlators in position space, sandwiched between the vacuum and a hadron state (e.g. pion), in order to access hadronic light-cone distribution amplitudes (DAs). In this way the renormalization problem for composite lattice operators is avoided altogether, and the connection to the DA is done using perturbation theory in the continuum. As an example, the correlation function of two electromagnetic currents is calculated to the next-to-next-to-leading order accuracy in perturbation theory and including the twist-four corrections. We argue that this strategy is fully competitive with direct lattice measurements of the moments of the DA, defined as matrix elements of local operators, and offers new insight in the space-time picture of hard exclusive reactions. PACS  12.38.-t, 14.20.Dh; 13.40.Gp     

Supersymmetric quantum mechanics and stochastic processes in curved configuration space

The euclidean functional integral of supersymmetric quantum mechanics on a riemannian manifold is reduced to a gaussian by generalizing Nicolai's transformation to a case with lagrangian quartic in the fermion variables. The transformation defines a stochastic process whose drift satisfies the potential conditions with vanishing local vorticity.