共查询到20条相似文献,搜索用时 31 毫秒
1.
The threshold behaviour of pion production presented in our earlier work is successfully compared with the new SPEAR data. By using duality and sum rules we derive FT(π+)(x) ≈ FL(π+)(x) ≈ FT(π0)(x) ? FL(π0)(x) for x near 1. An accompanying results is for large s. 相似文献
2.
Victor Elias 《Physics letters. [Part B]》1977,68(4):335-338
The Callan-Gross relation is shown to be consistent with MIT-SLAC data for for x ? 0.33 in deep inelastic eN scattering, despite the fact that these data are taken in the large Q2 region where F1 and F2 individually exhibit scaling violation. Comparison is made with asymptotic freedom predictions, and color excitation is proposed to explain large values of at small x. 相似文献
3.
Takashi Tonegawa 《Solid State Communications》1981,40(11):983-986
The transverse spin pair correlation function pxn=<SxmSxm+n>=<SxmSxm+n> is calculated exactly in the thermodynamic limit of the system described by the one-dimensional, isotropic, spin-, XY Hamiltonian . It is found that at absolute zero temperature (T = 0), the correlation function ρxn for n ≥ 0 is given by , , where the plus sign applies when J is positive and the minus sign applies when J is negative. From these the asymptotic behavior as n → ∞ of |?xn| at T = 0 is derived to be with a = 0.147088?. For finite temperatures, ρxn is calculated numerically. By using the results for ?xn, the transverse inverse correlation length and the wavenumber dependent transverse spin pair correlation function are also calculated exactly. 相似文献
4.
The solid electrolyte Ce1?xCaxO2-?x with the fluorite-type structure (Ca-doped CeO2) is a mixed conductor. Conduction occurs predominantly by migration of O2? ions via oxygen vacancies or by electrons, depending on the departure from stoichiometry. The ionic transference number σi/σi + σe was determined as a function of dopant concentration (0.07?x?0.15), temperature (400–800°C), and oxygen pressure by emf measurements with oxygen concentration cells. It is described by The entropy term S1(x) changes from 38.7k for x = 0.07 to 31.7k for x = 0.15; the enthalpy term, 5.42 eV, is independent of x and in excellent accord with semi-empirical calculations. 相似文献
5.
Gregory L. Tettemer Walter G. Planet 《Journal of Quantitative Spectroscopy & Radiative Transfer》1980,24(4):343-345
Intensities and half-widths of individual lines, over the temperature range 200–325°K in the 15 μm bands of 12C16O2, have been determined with a tunable diode laser spectrometer. Measurements were made on pure CO2 and on dilute CO2-in-N2 mixtures on the R-branches of the 0110-0000 and 0220-0110 transitions. Intensities are approximately equal to those listed in the AFGL compilation. The pressure-broadened half-widths follow the general relationship where n varies considerably from line to line but is always greater than . 相似文献
6.
Assuming that the sea quark distribution vanishes for x > 0.3, we analyse the F2Fe(x, Q2) and F2D(x, Q2) structure functions measured by the European Muon Collaboration in the framework of a thermodynamical model of the valence quarks. The experimental ratio is well reproduced over the whole x range by the ratio of two valence quark distributions at different temperatures T and confinement volumes V. We obtain TD?TFe≈3 MeV and . 相似文献
7.
8.
Small-angle scattering of long wavelength neutrons from an Fe65Ni35 single crystal has been measured with the applied magnetic field (6.2 kG) parallel and perpendicular to the scattering vector of the elastic scattering over the temperature range from 25 to 422°C (Tc = 227°C). The scattering cross sections due to the longitudinal spin fluctuation have been analyzed by means of Guinier's approximation , where the forward cross section (dσ/dω)0 is proportional to n, which is the number of atoms in a paramagnetic cluster, and Rg is the radius of gyration of the cluster. The empirical relation between n and Rg is = 0.298 × Rg2.34 to be compared with that calculated for a simple spherical cluster model n = 1.274 Rg3. 相似文献
9.
The longitudinal conductivity of a quasi-one-dimensional metal is calculated for the case T?ωD (ωD being the limiting phonon frequency) and ωDl1/v?1 where l1 is the effective mean free path determined by impurity and phonon scattering: is the impurity mean free path. The conductivity is σ = (c1e2/πS)l3iv?2ωDλT for li?lph, σ = (c2e2/πS)vωD(λT)?2 for li?lph, λ being the dimensionless electron-phonon interaction constant, c1, c2 ~ 1, S = axay is the (xy) area per one chain. 相似文献
10.
R.J. Panlener R.N. Blumenthal J.E. Garnier 《Journal of Physics and Chemistry of Solids》1975,36(11):1213-1222
Thermogravimetric measurements were performed on nonstoichiometric CeO2?x in the temperature range 750–1500°C and from oxygen pressures of 10?2 to 10?26 atm. From this data the deviation from stoichiometry x = x(T, Po2) was determined. The thermodynamic quantities Δo2 and Δo2 were calculated in the region 0.001? x ? 0.3 and found to be independent of temperature.In the composition region 0.001< x < 0.006, the variation of Δo2 with x is consistent with a defect model involving randomly distributed doubly ionized oxygen vacancies. The experimental dependence of x and σ (electrical conductivity) is shown to be consistent with this model as Δo2 (≈ -10 eV) exhibits a slight dependence on x. It is postulated that the variation in Δo2 may result from lattice parameter increases with x, while the defects remain essentially randomly distributed.In the composition region 0.006 < x < 0.1, x ∝ with 1 < n < 5, and in the region 0.1 < x < 0.3, x ∝ with n increasing rapidly with x to n? 30. This behavior is believed to result from increasing defect interaction with increasing departures from stoichiometry. It is interesting to note that the ordered phase observed by Bevan and Kordis between CeO1·72 and CeO1·70 was not observed in this study at temperatures between 1300° and 1500°C. 相似文献
11.
Robert S. Mulliken 《Journal of Molecular Spectroscopy》1976,61(1):92-99
Predissociations in the y1Πg and Rydberg states of N2 (configurations and , respectively) and their likely causes, are discussed. Peaking of rotational intensity at unusually low J values, without sharp breaking off, is interpreted as due to case c? or case ci predissociation. Λ doubling in the y state, attributed to interactions with the state and with another, 1Σ+, state of the same electron configuration as x, is analyzed. From this analysis the location of the (unobserved) state, here labeled x′, is obtained. It is concluded that the predissociation in the Π+ levels of the y state is an indirect one mediated by the interaction with x′ coupled with predissociation of x′ by a state dissociating to atoms: combined, however, with perturbation of the y state by the k1Πg Rydberg state (configuration ), whose Π+ levels are completely predissociated. 相似文献
12.
Charalampos A. Kolassis 《Physics letters. A》1983,95(2):82-84
We consider a neutrino field with geodesic rays in interaction with a gravitational field admitting a Killing vector field nμ. It is found that for solutions of the Einstein-Weyl field equations the neutrino field ξA and the neutrino flux vector lμ are restricted by the equations: and , whereas s is a real constant. In the case of pure radiation neutrino fields these equations become: , , where p and s are in general real functions of the coordinates. 相似文献
13.
It is shown that the low-temperature conductivity in two-dimensional impurity band of n-type inversion layer under strong magnetic field is . Therefore the effective conductivity of inversion layer at Shubnikov-de Haas conductivity minima may be very high at low temperature. 相似文献
14.
The emission and excitation spectra of the aromatic thioketone xanthione have been measured in Shpolskii matrices at 15 K. Under these conditions a sharp and rich vibrational structure is observed in the lowest triplet and the first and second excited singlet states. The phosphorescence excitation spectrum places the origin of the T1 ← S0 transition at 15 143 cm?1, while that of the absorption is tentatively assigned to the band at 16 093 cm?1. The phosphorescence spectrum, which shows only a weak CS stretch vibrational band, is dominated by ring vibrations. In accordance with the previous analysis of ODMR measurements, it is suggested that T1 and T2 states are energetically very close, thereby resulting in a lowest triplet state of heavily mixed n, , character. No mirror-image relationship is found between the relatively strong S2 → S0 fluorescence and the excitation spectrum of the transition. The latter is dominated by a long, pronounced 336-cm?1 progression. 相似文献
15.
The Auger 1 lifetime expression for degenerate n-type (Hg1?xCdx)Te has been derived by replacing the Fermi-Dirac distribution functions for the pair of Auger collision electrons with step functions. The lifetime is calculated as a function of carrier concentration, n0 for several values of energy gap and temperature using a non-parabolic band structure. We find that for strong degeneracy, the lifetime, τAlsuD varies as n0?γ where 0.7 ?γ? 1 and that γ is dependent upon the energy gap. The relatively slow dependence of τAlD upon n0, compared to the non-degenerate case () is due to the dependence of τAl on the threshold energy which for the degenerate case is a linear function of the Fermi energy, hence, a function of n0. 相似文献
16.
《Annals of Physics》1985,161(2):337-359
The differential and total cross sections for the nuclear reaction (1+; T = 1, 15.1 MeV) + νμ are investigated for values of 50 ≤ Eνμ ≤ 300 MeV. An effective Hamiltonian for the above nuclear reaction is constructed from the neutrino-quark neutral current weak interaction, by first constructing the neutrino-nucleon neutral current interaction and then using the impulse approximation along with the non-relativistic reduction procedure. The Weinberg-Salam model is the basis of the calculations. Detailed expressions for the differential cross sections are derived including the nucleon momentum-dependent terms. The numerical results are obtained using the general 1p-shell wavefunctions of Cohen and Kurath. The sensitivity of the total cross sections to the nuclear models and to the Weinberg angle is studied. The corresponding anti-neutrino reaction is also investigated. The ratio is found to be independent of the nuclear wavefunctions but very sensitive to the Weinberg angle. Thus this observable can be used to determine the free parameter θw in a nuclear reaction, thereby complementing the studies involving free nucleons. The recoil polarization of the final nucleus 12C1(1+; T = 1, 15.1 MeV) is also studied and its importance is pointed out. 相似文献
17.
Otto Nachtmann 《Nuclear Physics B》1974,74(3):422-428
Recent experimental results on electroproduction off protons show that the ratio σ(ep → eK+Σ0)/σ(ep → eK+Λ) decreases strongly with increasing Q2. A simple argument is given in the framework of the quark parton model which could provide a qualitative understanding of this fact. The decrease of the Σ0/Λ ratio is related to the decrease of the ratio as Q2 increases, where are the usual structure functions for deep inelastic electron-nucleon scattering. 相似文献
18.
《Journal of Physics and Chemistry of Solids》2004,65(8-9):1381-1390
19.
We study the behavior of 〈σ0x(t)σnx(0)〉 and 〈σ0y(t)σny(0)〉 for the transverse Ising chain at the critical magnetic field at T = 0. Explicit results are obtained for the three distinct regions where t → ∞ and n → ∞with , , or where z is fixed of order one. In this latter region the general Painlevé V solution is shown to reduce to a Painlevé II function. We use our results to discuss the general problem of long-time behavior of Toda equations with slowly decaying initial values. 相似文献
20.
V Malathy Devi B Fridovich G.D Jones D.G.S Snyder 《Journal of Molecular Spectroscopy》1983,97(2):333-342
Line strengths and self- and nitrogen-broadened half-widths were measured for spectral lines in the ν3 and ν2 + ν4 bands of 12CH4 and 13CH4 from 2870–2883 cm?1 using a tunable diode laser spectrometer. From measurements made over a temperature range from 215 to 297 K, on samples of 12CH4 broadened with N2, we deduced that the average temperature coefficients n, defined as , of the Lorentz broadening coefficients for the ν3 and ν2 + ν4 bands of 12CH4 were 0.97 ± 0.03 and 0.89 ± 0.04, respectively. A smaller increase is observed in line half-width with increasing pressure for E-species lines, for both self- and nitrogen-broadening, than for other symmetry species lines over the range of pressures measured, 70 to 100 Torr. 相似文献