共查询到20条相似文献,搜索用时 421 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.
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.
A. Bunde 《Physics letters. A》1975,53(3):208-210
A correct calculation of the Ising model correlation function C(q) = 〈(S(q) ? 〈S(q)〉) (S(-q) ? 〈S(-q)〉)〉 in the MFA results in . Previous literature supposed a violation of this sum rule to be a characteristic disadvantage of this approximation. 相似文献
4.
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
5.
C.R. Leavens 《Solid State Communications》1976,19(4):395-397
The Eliashberg gap equations relate the transition temperature Tc of an isotropic superconductor to its electron-phonon spectral function α2F(ω) and Coulomb pseudopotential parameter . Recently the Eliashberg theory has been used to derive some supposedly rigorous results bearing on the problem of attaining higher superconducting transition temperatures: Bergmann and Rainer derived an expression for the functional derivative ; Allen and Dynes showed that in the asymptotic limit of very large and Leavens proved that for any isotropic superconductor kBTc ?0.2309A, where A is the area under its electron-phonon spectral function. In this letter we show that the result of Allen and Dynes is not compatible with the other results and is, in fact, incorrect. 相似文献
6.
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
7.
8.
We study the correlation function 〈σ0x(t)σnx(0)〉 of the transverse Ising model in a critical field whose hamiltonian is . At an arbitrary temperature T we relate the autocorrelation to a Fredholm determinant. Moreover at T = 0 the correlations are given by a Painlevé V function for all n. The long-time asymptotic behavior of this function is found and the connection problem is studied. This result contains oscillatory terms which are related to the density of states at the Brillouin zone boundary. 相似文献
9.
R. Sartor 《Physics letters. [Part B]》1977,69(1):6-8
By taking due account of momentum conservation, it is shown that, when ω is near the Fermi energy ωF, the imaginary part of the mass operator for an infinite Fermi system behaves like (ω ? ωF)p(k) where the exponent p(k) ? 2 depends on the interval in which is lying. In particular, the commonly asserted quadratic behaviour (ω ? ωF2 is shown to be true only for . It is explicity assumed that the Fermi system admits a perturbative type treatment. 相似文献
10.
The oscillatory part of the indirect interaction between two adatoms on a metal surface, separated by a large distance R, is examined for the jellium as well as for the tight-binding model. The asymptotic form of the interaction is derived from the singularity of its Fourier transform at wave number q = 2kF. For a substrate with a spherical Fermi surface, the interaction energy is proportional to . The fall-off is faster than the corresponding oscillatory interaction between two impurities in the bulk, which varies as . For substrates with a partially filled surface band, the interaction energy falls off much more slowly. Under simple assumptions, the interaction behaves as . Comparisons are made with the numerical calculations by Einstein and Schrieffer. The experimental results of Tsong on Re atoms adsorbed on W using field-ion microscopy is also discussed. 相似文献
11.
Mahiko Suzuki 《Nuclear Physics B》1974,69(2):413-425
By use of the generalized scaling sum rules the vector-axial vector interference terms in the scaling limit of the inelastic neutrino reactions are calculated from the absorptive parts of the single-pion photoproduction amplitudes at zero momentum transfer. The photoproduction amplitudes are evaluated by use of the results of multipole analysis. With the optimum values for the two parameters of the generalized scaling as determined in previous works, we have obtained F3νN(ω) which leads to good agreement with experiment in the ration of . However, the zeroth moment in turns out to be smaller than half of the value predicted in the fractionally charged quark model. 相似文献
12.
T. P. McPharlin D. O. Caldwell J. P. Cumalat A. M. Eisner D. L. Fancher R. J. Morrison F. V. Murphy T. R. Risser S. J. Yellin 《Physics letters. [Part B]》1980,90(4):479-484
Using 20.5 GeV electrons on protons, we measured inclusive π0's (of transverse momentum, pT, from 0 to 1.4 GeV/c) produced by virtual photons of energy, ν, from 4 to 16.5 GeV and four-momentum squared, q2, from ?1.8 to ?8.5 (GeV/c)2. Comparing with charged pion data, we find , supporting the quark model. Photon knockout of a quark is favored as the interpretation of these data because of scaling in z = Eπ/ν and similarity in z-dependence of other pion production data. Consistent with this interpretation are the dependence of 〈pT〉 on q2, the azimuthal dependence, and fits to the constituent interchange model. We also observe a possible pT?4 dependence at large |q2| over a limited pT range. 相似文献
13.
The dependence of inclusive cross sections of the production of hadrons on p⊥ (and also on x and √s) is calculated at high energy in the region of small p⊥ ? 1–2 GeV. The model of production and decay of quark-gluon strings is used under the simplest assumptions about the k⊥ dependence of the quark distributions in nucleons ~ exp(?γ1k2⊥) and about the form of the string fragmentation function where γ1 and γh are some constants. The theory reproduces all existing experimental data and yields the “seagull effect” for the dependence of 〈p⊥〉 on x. Predictions are given for the p⊥ dependence of the spectra of π± mesons produced at high energies at SPS and other future colliders. 相似文献
14.
J.G. Rushbrooke R.E. Ansorge C.P. Bust J.R. Carter W.W. Neale C. Moore R. Raja L. Voyvodic R.J. Walker W. Morris B.Y. Oh D.L. Parker G.A. Smith J. Whitmore 《Physics letters. [Part B]》1975,59(3):303-307
New 100 GeV/cp data are used to find moments of the difference between the p and pp topological cross sections. The mean multiplicity for annihilations at 100 GeV/c is estimated to be 9.06 ± 0.56, and the value of the quantity 〈n〉/D to be 2.75 ± 0.33. It is shown that appears at 100 GeV/c to have acquired an asymptotic form, Rn = s?αβn, with α and β constant. 相似文献
15.
R. Oppermann 《Solid State Communications》1982,44(8):1297-1299
An n-orbital model describing both elastic impurity scattering and exchange interaction is examined near its instability for itinerant ferromagnetism. At the critical point and at zero temperature, long range spin fluctuations cause anomalous enhancements of the density of states near the Fermi energy with in three-dimensions (3D) and with ln2|E ? EF| in 2D. An estimation of the conductivity in a continuum analog model reveals Ω -and ln2-corrections in 3D and 2D respectively. 相似文献
16.
We investigate transition strengths of right-handed weak charged currents in deep inelastic neutrino scattering, exploiting the dominance of p, n valence quarks in the nucleon. The energy dependence of σt and the average quantities 〈y〉 and 〈Q2〉 are shown to provide sensitive measures of new quark production thresholds and right-handed currents in scattering. With our analysis, the present data give an upper bound on the right to left hand structure function ratio of , above a threshold of W≈7.5 GeV. 相似文献
17.
Robert W. Field Richard A. Gottscho E. Miescher 《Journal of Molecular Spectroscopy》1975,58(3):394-413
No perturbation between two valence states of NO has ever been identified, although many valence-Rydberg and several Rydberg-Rydberg perturbations have been extensively studied. The first valence-valence crossing to be experimentally documented for NO is reported here and occurs between the 15N18O B2Π (v = 18) and B′2Δ (v = 1) levels. No level shifts larger than the detection limit of 0.1 cm?1 are observed at the crossings near and ; two crossings involving higher rotational levels could not be examined. Semi-empirical calculations of spin-orbit and Coriolis perturbation matrix elements indicate that although the electronic part of the interaction is large, a small vibrational factor renders the 15N18O B (v = 18) ? B′ (v = 1) perturbation unobservable. Semi-empirical estimates are given for all perturbation matrix elements of the operators and which connect states belonging to the configurations , , and . 相似文献
18.
I. Yotsuyanagi 《Nuclear Physics B》1978,134(2):242-260
An upper bound on the partially integrated inclusive cross section is obtained at high energy from unitarity and analyticity assumptions which are to be expected for a two-body scattering amplitude that satisfies the Mandelstam representation. This result is analogous to the fixed-angle bound on two-body scattering amplitudes derived by Kinoshita, Loeffel and Martin. The bound leads to strong constraints on the average multiplicity, the average transverse momentum and the total cross section; in particular . According to this, the energy dependence of average multiplicity and average transverse momentum favors logarithmic growth, at most. 相似文献
19.
Yu.M. Antipov V.A. Bessubov N.P. Budanov Yu.P. Gorin S.P. Denisov S.V. Klimenko A.A. Lebedev Yu.V. Mikhailov A.I. Petrukhin S.A. Polovnikov V.N. Roinishvili D.A. Stoyanova F.A. Yotch 《Physics letters. [Part B]》1978,76(2):235-236
The differential cross sections and of inclusive J/ψ production by 43 GeV/c π? off Be, Cu and W nuclei have been measured. Fitting we observed the increase of α with pt2. 相似文献
20.
A new variational wave function to describe the ground state and the excited states of a bound polaron is proposed. It is of the form . It is argued that this form is reasonable for all electron—phonon coupling α and all strengths β of the Coulomb potential. Numerical and analytical results are derived for the energy of the ground state and compared to existing results. Results for the energy of the lowest p-type excited state of the bound polaron are obtained. 相似文献