共查询到20条相似文献,搜索用时 258 毫秒
1.
Yu.B. Bushnin A.F. Dunaitsev R.I. Dzelyadin S.V. Golovkin V.F. Konstantinov V.P. Kubarovsky L.G. Landsberg V.M. Leontiev G.P. Makarov V.A. Mukhin V.G. Rybakov T.I. Petrunina Yu.N. Simonov V.V. Smirnov A.M. Zaitsev A. Zallo 《Physics letters. [Part B]》1976,64(1):102-106
The difference of the cross sections for deep inelastic scattering of muons with average momenta 21 GeV/c with right and left helicity at large angles, i.e., with large momentum transfer, has been measured. No statistically-significant dependence of cross sections on the longitudinal polarization of muons has been found, i.e. no parity-nonconservation effects in deep inelastic μN interaction have been observed. The magnitude of the cross-section asymmetry may be represented as R = β〈Q2〉 = (? 4 ± 6) × 10?3 〈Q2, (GeV/c)2〉. The limitations Go(μ) = (+ 6 ± 10)G have been obtained for the constant Go(μ) of vector-axial interaction (hadron, V-A). 相似文献
2.
H. Kleinert 《Physics letters. [Part B]》1976,62(1):77-80
In quark gluon theory with very small bare masses, -ψ, spontaneous breakdown of chiral symmetry generates sizable masses Mu, Md, Ms, … We find (. Scalar densities have well determined non-zero vaccum expectations at an SU(3) breaking of the vacuum c′ ≡ 〈0|u8|〉/〈0|uo|0〉 ≈ ? 16% 相似文献
3.
Absolute differential cross sections for elastic electron-proton scattering have been measured in a four-momentum transfer range up to 1.4 fm?2. Using a high pressure gas target system, we have obtained highly accurate data with a small normalization error of 0.5%. The electromagnetic form factors GE and GM have been extracted and the rms charge radius has been determined to be . The shape of the isovector spectral function near threshold shows a significant non-resonant contribution of the two-pion state. This enhancement is so strong that the derivative at q2 = 0 differs considerably from the usual vector meson dominance model value. This result is in good agreement with theoretical predictions. 相似文献
4.
The temperature dependence of the field emission flicker noise spectral density functions has been investigated for potassium adsorbed on tungsten (112) planes by a probe hole technique. By integration of the spectral density functions the noise power for different frequency intervals Δ? is obtained. From the exponential temperature dependence of noise power “activation energies” qΔ? are determined. Plots of these energies versus coverage show a similar “oscillating” behaviour as recently found for or which indicates phase transitions of the adsorbed potassium submonolayers. The noise activation energies are discussed in terms of existing models and a comparison is made between the experimental q values and surface diffusion energies Ed as determined by conventional methods. 相似文献
5.
T. Fukuda T. Nomura T. Shimoda K. Katori S. Shimoura K. Sueki H. Ogata 《Nuclear Physics A》1984,429(1):193-204
The longitudinal momentum transferred to a target nucleus (ΔP) has been studied for light-particle emission in the 14N-induced reaction on 232Th at 208 MeV. The transferred momentum was deduced by measuring folding angles between two fission fragments resulting from the sequential decay of the target-like nucleus. It was found that the fraction averaged over light-particle energy was about 0.68, almost independent of light-particle species and detection angle, where Pbeam is the initial momentum of the beam particle and Pout∥, the momentum component parallel to the beam carried away by the observed light particle. A possible mechanism for describing the phenomena is discussed. 相似文献
6.
Cyclotron resonance in n-GaP has been observed at 119 μm in pulsed magnetic fields up to 410 kG. From the experiments with the magnetic field parallel to the 〈100〉, 〈110〉 and 〈111〉 axes, it is concluded that the transverse effective mass for electron is and that the anisotropy factor of the conduction band is K = 7.9+3.2?2.0. An anomalous shape of the absorption curve was found in the magnetic field directions parallel to the crystal axes 〈110〉 and 〈111〉. 相似文献
7.
We construct a potential for qurkonium systems using as the basic ingredients the gluon condensate, i.e., 〈0∥GμνaGμνa∥0〉 ≠ 0 to incorporate nonperturbative effects and using quark screening. The potential is able to account satisfactorily for the s, c and b bound states with a flavor independent, essentially constant value for the effective coupling constant . We also investigate heavier quark systems with the constant and find that for quark mass ? 20 GeV the potential is essentially coulombic. 相似文献
8.
Exclusive decays such as G → ππ are studied in the framework ofperturbative QCD. We discuss the possibility of the constituent gluons' virtualness scaling as the glueball mass MG, which is a picture equivalent to a glueball containing a few slow-moving, heavy gluons. In this case, the decay rate exhibits a pinch singularity which enhances it by a factor of order (MG2/mq2)2 over the dimensional scaling expectation. This singularity is partially suppressed by Sudakov effects which reduce the enhancement factor to . 相似文献
9.
B.L. Ioffe 《Nuclear Physics B》1981,188(2):317-341
The polarization operator of quark currents with baryon quantum numbers is considered in quantum chromodynamics. The non-zero mean vacuum values of the field operator products are taken into account. The sum rules are obtained assuming that in the virtuality region ~1 GeV, among the mean vacuum values violating the chiral invariance, the most important is . Saturating these sum rules by the lowest baryonic states one is able to calculate the masses of the isobar Δ and nucleon N, MΔ = 1.4 GeV, MN = 1 GeV, up to 15% through the known value . The mass splitting in the baryonic decuplet is calculated in first order in the current strange quark mass ms = 150 MeV. Certain results for other baryonic resonances have also been obtained. 相似文献
10.
We studied the energy width and the width in reciprocal space Δq of the central mode of SrTiO3 above Tc. At Tc+4° we observed an energy width of about 6×10?7 eV. If the measured Δq is interpreted by a correlation length we obtain . 相似文献
11.
The microwave spectra of CH235Cl and CH237Cl have been observed and lines assigned to the gauche form. The rotational constants in MHz and distortion constants in KHz are: C3H5CH235Cl, A = 11745.65, B = 2047.274, C = 1886.622, ΔJ = 0.85, ΔJK = ? 0.9, ΔK = 44., δJ = ? 0.099, δK = 19.1, C3H5CH237Cl, A = 11691.61B = 1997.664, C = 1842.823, ΔJ = 0.7, ΔJK = ? 64.6, ΔK = 2400, δJ = 0.19, δK = ? 67. 相似文献
12.
William H. Hamill 《Journal of Physics and Chemistry of Solids》1982,43(6):559-562
The time- and temperature-dependent drift mobility μd for dispersive transients in disordered solids is in terms of distance L, field E and transit time tT. Since current I ∝ tsu?(1?α) for t <Tand 0<α<1 by Scher-Montroll theory for hopping among localized states, it follows that where τ≈ 10?13s is estimated. Further and the activation energy Δ0 is time independent. On this basis Δ for the carbazole polymers is ca. zero, that for a-Se is ca. 0.05 eV, and that for a-As2Se3 is 0.35 eV rather than 0.5, 0.3 and 0.6 eV respectively on a phenomenological basis for μd(T,t). Trap-controlled hopping transport may be excluded. Time-resolved optical studies of excess carrier recombination supplement mobility measurements in a-Si:H and a-As2Se3 as well as other systems. Combined results suggest a dielectric response mechanism in which the time-dependent hopping frequency of localized carriers ν ∝ tα?1 arises from distortion of the medium at localization sites. This is satisfied by Δ(T,t) = Δ0+(1?α)KTT ln(t/τ) where τ is the mean initial localization time of the carrier, 10?13?10?12s, Δio is the height of the barrier at T, and 0<α<l. Consequently ν = ν0(t/τ)α?1 exp(frsol|?Δ0/KT) which applies also to bimolecular recombination. 相似文献
13.
The rotational motion of the OH? ion was studied in cubic NaOH at 575 K with quasielastic incoherent neutron scattering. The data are compared to two simple models yielding values for the radius of rotation R, the translational mean square displacement 〈u2〉H, the rotational jump rate τ?1 and the rotational diffusion coefficient DR. The following parameter values are obtained: (a) rotational jump model: , , (b) rotational diffusion model: . 相似文献
14.
J. Kwiatkowski 《Reports on Mathematical Physics》1973,4(3):203-210
The purpose of this paper is to prove the following theorem.Theorem. Given a countable subset Λ on the circle K and an integer-valued function n(λ) on Λ, there exists a dynamical system with discrete spectrum (X,,μ,T) such that Λ is the set of all eigenvalues of T and n(λ) is the multiplicity function of T if and only if there exist two systems of subgroups {Gi}i∈N and of the circle such that Λ = G ∪ S and where . 相似文献
15.
C.A. Piketty 《Nuclear Physics B》1974,68(1):44-65
We have evaluated the parity-violation contribution in atoms in the framework of SO(3) gauge theory. Various hadronic models have been used: first, for simplicity, the unrealistic five-quark one, next, others involving three ordinary SU(3) triplets for which all unwanted strangeness-changing processes are suppressed, up to order . In the free quark approximation, we obtain quite similar parity-violation effects which are proportional to (ΔM2 is the difference of squared masses of leptons (MX02 ? Mν2 = MX02), or of quarks (ΔMq2)). Namely, in large atoms (Z ? 1) the electronic contribution which is proportional to gives the largest effect (are the spin, momentum operators and mass of the lepton). Parity-violating effects in SO(3) gauge models are ?10?4 smaller than those evaluated in the Weinberg theory with a neutral parity-violating current and will remain undetectable in the near future. 相似文献
16.
H. Falk 《Physica A》1980,104(3):475-479
The (discrete-time) Glauber model is considered for a one-dimensional system of spins sj = ±1 with nearest-neighbor Ising interaction . The Jj = ±J are treated as random variables with an arbitrary joint probability p(J). The exact time-dependent average 〈sj〉t is determined, and from it the “quenched” average is explicitly found. 相似文献
17.
The fine structures of the (ν1 + ν2) and (ν2 + ν3) combination bands of ozone in the 5.7-μm region have been recorded and analyzed. The two vibrational states are coupled through Coriolis and second-order distortion terms. The interaction has been treated by the numerical diagonalization of the secular determinant for the two coupled states. With the centrifugal distortion parameters fixed to the ground state values, the following constants have been obtained: ν1 + ν2 = 1796.266, A110 = 3.6104, B110 = 0.44145, , ν2 + ν3 = 1726.526, A011 = 3.5537, B011 = 0.43982, , Y13 = ?0.466, and X13 = ?0.010 cm?1. In addition, the following anharmonic constants have been obtained: x12 = ?7.821 and x23 = ?16.494 cm?1. The value of the dipole moment ratio, , is 1.30 ± 0.10. 相似文献
18.
A formula at low temperature for the function G() = Iλλ6 has been derived in terms of configuration curve theory and checked on luminescence spectra near 77 K. The vibrational quantum in the excited state has been calculated from the decrease of G(), where λM is the wavelength of the maxima of G at low temperature, as a function of temperature. 相似文献
19.
J. Leotin J.C. Ousset R. Barbaste S. Askenazy M.S. Skolnick R.A. Stradling G. Poiblaud 《Solid State Communications》1975,16(4):363-366
The first observation of cyclotron resonance in n-type GaP is reported. The electrons were thermally excited at a temperature of 100 K and the resonance was observed at submillimetre wavelengths (337 μm) using a pulsed magnetic field of 0–300 kG. From experiments with B∥〈100〉, 〈110〉 and 〈111〉 it was found that the transverse effective mass for electrons is and that the anisotropy factor for the conduction band ellipsoids is K = 20+10-6. 相似文献
20.
M. Haguenauer P. Lundborg C. Matteuzzi G. Poulard L. Ramello S. Bonetti D. Cavalli D. Pedrini A. Pullia Ph. Heusse 《Physics letters. [Part B]》1981,100(2):185-190
Quark fragmentation functions are studied with ≈3500 charged current events induced in the bubble chamber Gargamelle by neutrinos of the SPS wide band beam, with 〈Eν〉 ≈ 25 GeV. The Q2 and W2 regions covered by this experiment are Q2 ≈ 0–40 GeV2 and W2 ≈ 1–100 GeV2, the mean values being 〈Q2〉 = 6.5 GeV2, 〈W2〉 = 22GeV2. A correlation between the variables and is found in the data in the region Q2 = 1–10 GeV2, which can be explained in terms of higher twist effects. These effects reproduce the Q2 evolution of the non-singlet moments of the fragmentation function without any need for logarithmic terms. 相似文献