共查询到20条相似文献,搜索用时 31 毫秒
1.
QCD predictions of hadronic multiplicity moments in jets, including corrections of relative order , are presented. They agree with e+e? annihilation data for reasonable values of αs, but the corrections are so large that terms of yet higher order are unlikely to be negligible. 相似文献
2.
A. Ali 《Physics letters. [Part B]》1982,110(1):67-72
The QCD effective coupling constant αs(Q2) is determined by comparing the O(αs)2 jet-distributions with the high-energy e+e? data from PETRA. We get αs(Q2 = 1225 GeV2) = 0.125 ± 0.01, which corresponds to with five flavours. 相似文献
3.
The total cross section for the production of a muon pair of invariant mass Q2via the Drell-Yan mechanism and the Feynman xF differential cross section are calculated in QCD retaining all terms up to order αs(Q2. The calculations are performed using dimensional regularisation of the intermediary infrared and collinear singularities, but we present our results in a form independent of such details. The corrections to both these cross sections coming from radiative corrections to the lowest-order annihilation diagram are found to be large at present values of Q2 and S when the cross section is expressed in terms of parton densities derived from leptonproduction, for all Drell-Yan processes of practical interest. Numerical calculations are presented which show, for any reasonable parametrisation of the parton densities, that the neglect of higher-order terms in αs(Q2) is not justifiable. The quark-gluon diagrams on the other hand give small corrections in this order and are only important for PP scattering. 相似文献
4.
Jan T. łopuszański 《Reports on Mathematical Physics》1976,9(3):301-307
It is shown that for spinorial charges Q(L))α (α = 1, 2, L = 1, …, S) satisfying the commutation relations where Q is a scalar charge commuting with the spinor charges as well aswith the energy- momentum vector Pμ, there can exist several different multiplets for free massive scalar and spinor fields. 相似文献
5.
Bernhard F. Gächter 《Journal of Molecular Spectroscopy》1976,63(1):1-22
The irreducible components of the Raman scattering tensor operator under the symmetry of a general point group are calculated. The unitary transformations U(ΓγΓksΓk′s′, ρσ) from the Cartesian and spherical components, respectively, to the irreducible components for the 32 crystallographic point groups are collected in tables. As an example the unitary transformation U(ΓγΓksΓk′s′, ρσ) is used to discuss the behavior of the scattering tensor in a resonance Raman experiment. With the help of the general formalism the scattering tensor for electronic Raman transitions of transition metal ions is calculated. As an example the scattering tensors of electronic Raman transitions within the 5T2 state of the high-spin trigonal distorted octahedral Fe2+ are calculated and the refinement of the selection rules is discussed. 相似文献
6.
In an effort to develop a quantitative check of asymptotically free color-gauge theories, we analyze the logarithmic corrections to ξ-scaling coming from anomalous dimensions and coefficient functions of twist-two operators and compare with electroproduction data for 1 ? Q2 ? 16 GeV2. Excellent agreement is obtained using for the effective quark-gluon coupling in the color-gauge theory. Effects of higher-twist operators are suppressed by powers of . We use data from the resonance region to show , in agreement with theoretical expectations. Our fit to νW2 in the scaling region also describes the resonance region in the sense of Bloom-gilman local duality. We show that local duality is a consequence of the moment predictions obtained from the operator-product expansion in quantum chromodynamics. We resolve a paradox associated with local duality and spin-zero targets. Present measurements of at large x and Q2 are systematically higher than our predictions. 相似文献
7.
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
8.
The influence of lowest-order QCD corrections on the Drell-Yan cross section is determined and compared with the asymptotic freedom (AF) corrections. The perturbative calculation exhibits the AF-characteristics of a (strongly) rising Q2-dependence for √τ?0.1 (qg-scattering) and falling for √τ?0.2 (qq?-annihilation). Qualitative agreement between the two calculation methods in the entire √τ-range is obtained with αs = 0.3. 相似文献
9.
Nuclear spectroscopic quadrupole moments of the radioactive isotopes 131Cs, 132Cs, and 136Cs have been determined from the hyperfine structure of the state by the level crossing method. The results including a Sternheimer correction are: , , . The quadrupole moments of all the Cs isotopes from A = 131 to A = 137 are recalculated. It is shown, that nuclear quadrupole moments of a specific isotope obtained from different atomic P-states only agree within the limits of error after application of the Sternheimer correction. The increase of Qs with decreasing neutron number conforms with other observations and theoretical calculations stating that for elements around Z = 55 nuclear deformation develops below N = 82. The staggering of the sign of Qs may be interpreted as consequence of an oblate-prolate degeneracy of the nuclear energy surface. Some magnetic moments have been slightly improved: , (corrected for diamagnetism). 相似文献
10.
We calculate the next-to-leading order QCD corrections in the scheme to the coefficient functions in an operator product expansion of the amplitude T(q2, p2) for the process , flavour non-singlet meson in which ?q2 is large and ?p2 ? 0. For an asymptotic wave function the complete O(αs) correction for a pseudoscalar meson is about 16% for p2 = 0 and αs = 0.3; most of this correction can be removed by using a modified evolution equation for the wave function, leaving a correction of about 7%. For large p2 the complete O(αs) correction for a pseudoscalar meson is about 10%. We discuss how our results can be combined with similar calculations for the pion form factor Fπ(Q2) to give a prediction: Fπ(Q2) = Aαs(Q2)Tπ2(q2, 0)(1 + Bαs) that is independent of the as yet unknown two-loop anomalous dimension matrix. 相似文献
11.
Taisuke Nakanaga Shigeo Kondo Shinnosuke Saëki 《Journal of Molecular Spectroscopy》1980,81(2):413-423
The Coriolis interactions between ν1 and ν3, and between ν2 and ν3 in SO2 have been analyzed to obtain the signs of the products and . It has been found that both of the signs of these products are positive. Then, relative signs of () have been determined using the calculated values of the Coriolis zeta constants for the present definition of the normal coordinates. The obtained sign combination of () is ±(+?+), which agrees with the one predicted by the molecular orbital calculations. Using the sign combination (+?+), the polar tensors of S and O atoms were also calculated. 相似文献
12.
Moshe Moshe 《Physics letters. [Part B]》1981,98(4):297-300
Though high twist terms are becoming important as x→1, or equivalently, in large n moments, their detection in this regime in deep inelastic lepton scattering needs special caution. The high order terms in the twist two component are strongly dependent on n; one finds that at the perturbative expansion is invalid whereas higher twist terms are important at . Since grows very fast with n the necessary requirement for any deep inelastic phenomenological analysis, namely , cannot hold for too large moments. The scheme dependence of ak, αk and bk is also discussed. 相似文献
13.
y.И. caфpoнoвa 《Journal of Quantitative Spectroscopy & Radiative Transfer》1975,15(3):231-242
Energies and dipole matrix elements have been calculated for He, Li, Be, B, C, N, O, F, and Ne-like ions (configurations 1s22sn12pn2?1s22sn1?12pn2+1). The Hartree-Fock energy, the correlation energy, and relativistic corrections were taken into account. Relativistic corrections were obtained by computing the entire quantity HB. Numerical results are presented for energies of the terms in the form , and for the fine structure of the terms in the form . Dipole matrix elements are required for calculation of oscillator strengths or transition probabilities. For the dipole matrix elements, two terms of the expansion in have been obtained. Numerical results are presented in the form P(a, a′) = (a/Z)[1 + (τ/Z)]. 相似文献
14.
We analyse the effects of logarithmic corrections due to asymptotic freedom in the potential describing short-range forces in charmonium. This allows us to show that due to the size of the effective quark-gluon coupling (), the wave function extensions are much larger than the region of space where asymptotic freedom really has predictive power. The resulting ambiguities in the spin-dependent medium-range forces are explored. Also, such a value of αs makes perturbative calculations of widths unreliable. We point out that the situation is not significantly improved for quark masses of 5 GeV. Indeed, below 20 GeV, short-range forces play a marginal role as compared to confinement forces. 相似文献
15.
From the scaling law for the s-channel partial wave amplitudes, which guarantees simultaneously t-channel unitarity at threshold t = 4μ2 and s-channel unitarity, we derive: (i) The intercept α(0) of the Pomeron is always one, if α(4μ2) > 1. (ii) The total and the elastic cross sections are bounded from below for s → ∞. where α(4μ2) and δ(4μ2) are the position and the type of te Pomeron singularity (J ? α(4μ2))?1?δ(4μ2) at t = 4μ2. (iii) The type of the Pomeron singularity δ(4μ2) is restricted: either or . 相似文献
16.
The average multiplicity in deep inelastic electro- and neutrinoproduction at large ω(ω~s/Q2 + 1) is related in Feynman's version of the parton model to the average multiplicities in high-energy electron-positron annihilation and hadron-hadron scattering. The relation is: , where Ce+e? and Ch are, respectively, the coefficients of ln(s/M1⊥2) in the multiplicities from e+-e? and P-P in to hadrons, and M1⊥ is an average transverse mass. 相似文献
17.
H. Schmeing J.C. Hardy R.L. Graham J.S. Geiger K.P. Jackson 《Physics letters. [Part B]》1973,44(5):449-452
Beta-delayed γ-rays have been observed from the decay of . A decay scheme is proposed based on γ-γ and β+-γ coincidence measurements. The total decay energy was measured to be QEC = 5057 ± 135 keV. The value is compared with mass predictions. 相似文献
18.
19.
The deep inelastic structure function D(ω, q2) is calculated in the leading log approximation for . For larger ω up to ( the influence of reggeon cuts proves to slow down the growth of the structure function. A reggeon diagram technique is developed, and D is calculated up to a pre-exponent O(1), leading to D(ω, q2) ∝ q2 for . By assuming the reggeon diagrams when ω is still greater, one can expect to obtain a strong coupling behaviour: D(ω, q2) ∝ q2(ln ω)η (η <2). 相似文献
20.
t-channel unitarity equations are derived for n-particle overlap functions. Together with s-channel unitarity they lead to scaling laws for the inelastic s-channel partial-wave amplitudes in the limits . Assuming the validity of the scaling law in the whole range, allowed by s-channel unitarity — i.e. for we obtain constant production cross sections σ(n)(s) at high energies s → ∞ up to s factors. 相似文献