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TheW andQ 2 dependence of the transverse momentum of the forward-going hadrons in deep inelastic neutrino charged current interactions on neon is studied. The data were obtained by exposing BEBC filled with a Ne/H2 mixture to the CERN SPS wide-band neutrino beam. The data on average transverse momentum are compared to a model which includes first order QCD, intrinsic quark momentum in the nucleon and Fermi motion, as well as a simple model for hadronization. The model is found to describe the data well. Values of s =0.16±0.02(stat)±0.02(syst.)±0.03(frag.) at an averageQ 2 of 15.4±0.4 GeV2/c2 and (stat.) –90 +100 (syst.) –90 +130 , (frag.) MeV/v for three flavours are extracted.  相似文献   

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Recent experiments at LEAR have found surprisingly large branching ratios for reactions $\bar NN \to \phi \pi $ from S-wave initial states while noφπ production is observed from P states of the $\bar pp$ system. Also, noφπ is seen in radiative J/ψ decays even though the rate forωπ is substantial. We calculate theφπ production rates for these three cases viaKK* intermediate states and $K\bar K$ rescattering using the dispersion relation technique; we find that the largeφπ rate in $\bar pp$ annihilations from S states can be reproduced with a reasonable cut-off for the dispersion integral; for J/ψ decays the calculatedφπ rate is compatible with the observed upper limit. We would, however, expectφπ to be seen from $\bar pp$ P-states, in contrast to experimental findings. Yet the branching ratio for $\bar pp \to K*\bar K$ via isospinI = 1 of $\bar pp$ ,1 P 1 state is not known; and therefore no definite conclusion can be drawn. We also compare the Dalitz plots we obtain for directφ production and forφ production via rescattering. Clear differences between the two theoretical distributions are observed; yet very high precision data would be required to establish the origin — direct production or rescattering — of theφ mesons. This observation supports the use of the isobar model in data analyses.  相似文献   

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The pressure-dependence of mechanical, electronic and thermodynamic properties of metastable (L12 type) and stable (D023 type) Al3Zr precipitations in Al–Li alloys were investigated by employing the first-principle calculations. The calculated equilibrium parameters are in good agreement with experimental and previous calculation results available. Elastic properties including bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and universal anisotropic index are determined by Voigt–Reuss–Hill approximation. It is found that for both phases, external pressure can improve the mechanical stability, ductility and plasticity. The electronic structures are determined to reveal the bonding characteristics of both phases. In addition, both phonon method and Gibbs program have been proposed to predict thermodynamic properties of two phases. All of these results can help to have a better understanding of the physical and chemical properties of Al3Zr precipitations in Al–Li alloy. And can offer theoretical guidance for the weight lighting, energy conservation and emissions reduction in the design of new aluminium alloys.  相似文献   

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A quantum dynamic calculation on a five-dimensional O2/LiF (001) model system is performed using the multi-configuration time-dependent Hartree method. The obtained results show that the mechanism of rotational and diffractive excitation in details: Comparison with the rotational excited state, the initially non-rotational state is seen to favor the inelastic scattering in the rotational excitation process. The surface corrugation can damp the quantum interferences and produce a greater amount of rotational inelastic scattering at the expense of the elastic process in the rotational excitation process. The diffraction process and the average energy transferred into the rotational and diffractive mode are also discussed.  相似文献   

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We present calculations of coherent photoproduction of vector mesons(J/ψ and Υ) with leading-order parton distribution functions to check new kinds of corrections of the DGLAP equations and nuclear modifications.The input gluon distribution of the proton is the dynamical parton model from the DGLAP equations with GLR-MQZRS(Gribov-Levin-Ryskin,Mueller-Qiu,Zhu-Ruan-Shen) modifications.From comparison between several other gluon distribution models,we find that the dynamical gluon distribution fits with the results of meson photoproduction experiments in the high energy region.The calculation of the differential cross sections using dynamical and other gluon distributions is compared with the experimental data from the HERA,ZEUS and LHCb Collaborations.Although there is little data for the rapidity distribution of vector meson photoproduction near zero rapidity,the dynamical gluon distribution works well with the data in the large rapidity region.  相似文献   

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A joint theoretical analysis is made of the binding energies of the ground and excited states of the four-particle hypernuclei and and the cross sections of low-energy p-scattering. We propose concrete variants of paired central spin-and charge-dependent n-potentials which are consistent with experiment.Translated from Izvestiya Vyssikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 62–65, May, 1982.  相似文献   

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Far-field head-related transfer functions(HRTFs) vary with source direction, frequency and individual. Correspondingly, the dimensionality of a full set of HRTFs is huge and measurement or calculation of individualized HRTFs with high directional resolution could be difficult. A method to construct HRTFs with high directional resolution from a small set of directional measurements or calculations is proposed in present paper. Based on tensor decomposition of HRTFs, far-field HRTFs are decomposed...  相似文献   

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ZFSR experiments on CeSb and DySb reveal fast spin dynamics even in their magnetically ordered states below 16.2 and 9.5 K, respectively. Above these first order transitions both pnictides exhibit strong frequency shifts in TF pointing to some magnetic precursors. The signals below T N show spontaneous rotating contributions. For CeSb several commensurately modulated antiferromagnetic phases containing paramagnetic sheets are confirmed. For DySb our data favor a CoO type structure in contrast to the MnO structure proposed from neutron diffraction.Part of this work was funded by the German Federal Minister for Research and Technology (BMFT) under contracts No 03-LI3-BRA and 03-KA2-TUM-4.  相似文献   

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Data on 6π states produced ine + e ? annihilation and diffractive photoproduction are analysed together. The simplest interpretation is in terms of two major contributions from resonances. One, in the isotopic spin symmetry state (321), peaks at 2.1 GeV and the other, in the isotopic spin symmetry state (411), peaks at 1.8 GeV. The former is a candidate for a new ρ-meson. The latter could be an additional ρ-meson, but the possibility that it is a manifestation of the known ρ 2 -meson, distorted by threshold effects, cannot be ruled out.  相似文献   

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In real-world network evolution, the aging effect is universal. We propose a microscopic model for aging networks,which suggests that the activity of a vertex is the result of the competition of two factors: pullulatlon and decrepitude. By incorporating the pullulation factor into previous models of aging networks, both the global and individual aging effect curves in our model are single peaked, which agrees with the empirical data well. This model can generate networks with scale-free degree distribution, large clustering coefficient and small average distance when the decrepitude intensity is small and the network size not very large. The results of our model show that pullulation may be one of the most important factors affecting the structure and function of aging networks and should not be neglected at all.  相似文献   

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We propose a model of weighted networks in which the structural evolution is coupled with weight dynamics. Based on a simple merging and regeneration process, the model gives powel-law distributions of degree, strength and weight, as observed in many real networks. It should be emphasized that, in our model, the nontrivial degree-strength correlation can be reproduced and in agreement with empirical data. Moreover, the size-growing evolution model is also presented to meet the properties of real-world systems.  相似文献   

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The thermodynamical behaviors of E′ centers in 8 quartz samples from core XJ33-2-1 recovered in the Zhujiang Mouth Basin were measured by electron spin resonance (ESR) technique. The E′ ESR spectral intensity of samples before any laboratory treatment was measured and expressed asI 1. The samples were then annealed at 300°C or 350°C for 60 min. The E′ ESR spectral intensity measured after this procedure is expressed asI 2. The ratios ofI 1, toI 2 for the samples increase with the sample depth (from 320 to 3972 m), showing that there is a correlation between this ratio and the storage temperature of samples. Therefore the ratio ofI 1/I 2 can be used as an ESR paleothermometer. Besides the temperature, we must take into account the period of time for which the samples have been buried since their deposition, because we find that the ratiosI 1/I 2 (from 0.293 to 0.941) are closely related to the sediment ages (from 1.5 to 27.5 Ma), with a correlation coefficient of 0.98 or 0.99 obtained by linear or exponential regression, respectively. This relation can be explained by the increase of E′ center concentration in quartz samples with the sedimentation age.  相似文献   

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We investigate the effect of temperature on the structure and shear response of a Σ11 asymmetric tilt grain boundary in a classical embedded-atom model of elemental copper using molecular dynamics simulations. As the temperature is increased the structure of the boundary disorders considerably, but with a boundary width that remains finite at the melting point. The disordering of the boundary structure becomes significant for homologous temperatures above 0.83 (1100?K). As temperature increases above this point the boundary width and roughness increases monotonically. Near the temperature where the boundary starts to disorder we observe a change in the temperature dependence of the ideal shear strength of the boundary, as well as the value of the coupling parameter β, defined as the ratio of the velocity of relative translation of the grains parallel to the boundary plane to that corresponding to the motion of the boundary normal to its plane.  相似文献   

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High and fluctuating salinity is characteristic for coastal salt marshes, which strongly affect the physiology of halophytes consequently resulting in changes in stable isotope distribution. The natural abundance of stable isotopes (δ13C and δ15N) of the halophyte plant Salicornia brachiata and physico-chemical characteristics of soils were analysed in order to investigate the relationship of stable isotope distribution in different populations in a growing period in the coastal area of Gujarat, India. Aboveground and belowground biomass of S. brachiata was collected from six different populations at five times (September 2014, November 2014, January 2015, March 2015 and May 2015). The δ13C values in aboveground (?30.8 to ?23.6?‰, average: ?26.6?±?0.4?‰) and belowground biomass (?30.0 to ?23.1?‰, average: ?26.3?±?0.4?‰) were similar. The δ13C values were positively correlated with soil salinity and Na concentration, and negatively correlated with soil mineral nitrogen. The δ15N values of aboveground (6.7–16.1?‰, average: 9.6?±?0.4?‰) were comparatively higher than belowground biomass (5.4–13.2?‰, average: 7.8?±?0.3?‰). The δ15N values were negatively correlated with soil available P. We conclude that the variation in δ13C values of S. brachiata was possibly caused by soil salinity (associated Na content) and N limitation which demonstrates the potential of δ13C as an indicator of stress in plants.  相似文献   

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