共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
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
3.
The predictions of perturbative QCD are derived in the deep euclidean region, whereas the physical region for most observables is timelike. The confrontation of these predictions with experiment thus necessitates an analytic continuation. This we find introduces large higher order corrections in terms of αs(|Q2|), the usual choice ofperturbative expansion parameter. These corrections are naturally absorbed by changing to the expansion parameter , where αs(Q2)n is the leading term in the spacelike region. For the intermediate range of Q2 experimentally accessible at present, where is significantly smaller than αs(|Q2|), we find the resulting phenomenology is improved. In particular, we demonstrate how the values of obtained from analyses of quarkonium decays become consistent. 相似文献
4.
Emili Elizalde 《Physics letters. [Part B]》1982,115(4):307-309
The confining properties of the leading logarithm approximation to the effective lagrangian [ with g(t) a running coupling function of t = log(F2/μ4)] are seen to disappear when the second and the third approximations of the β-function power series expansion are considered. 相似文献
5.
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
6.
Given a mapping , whose bifurcation points accumulate at λ = Λ∞, it is shown that the iterates converge to a function ψ(μ,y)asp→∞, where X∞ maximizes . The function ψ is universal up to scaling in μ and y, and satisfies ψ(μ/δ,ψ(μ/δ,?y/α)) = ?α?1ψ(μ,y). This result generalizes the well-known Feigenbaum universal function g(y) with g(g(?y/α)) = ?g(y/α, which is the special case for μ = 0. 相似文献
7.
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
8.
A forward dispersion relation cannot be applied to charged particle scattering amplitudes unless the influence of the Coulomb interaction is explicitly considered. Earlier studies have shown how Coulomb effects can be taken into account when direct (s-channel or bound-state) poles are investigated. In this paper we extend the Coulomb modification to include I = 0 exchange (u-channel) processes as well. We then apply a forward dispersion relation to empirical d + α, p + d and n + d elastic scattering amplitudes which contain both direct and exchange poles with and without Coulomb effects. We obtain detailed and model-independent information on the following vertices: 6Li-α-d (S- and D-state) 4He-d-d, 3He-d-p, 3H-d-n and d-p-n. From the coupling constants we calculate the asymptotic normalization (spectroscopic factors) C21 of the corresponding cluster wave functions, which become: , , C20(α, dd) < 2, , . 相似文献
9.
We study the potentials of the form U(r)=?r?1+λV(r), , and show that the energy levels satisfy the inequalities to first order in λ, where Nc denotes the coulombic principal quantum number and l the angular momentum. Similarly for potentials , we prove to first order in λ that , where NH denotes the harmonic oscillator quantum number. In the latter case, we give also quantitative restrictions on the relative positions at the lth and (l+1)th states. 相似文献
10.
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
11.
We have obtained a least upper bound, , on the critical temperature Tc of an isotropic superconductor with paramagnetic impurities described by the scattering matrix t for fixed values of μ1. We have also obtained the corresponding optimal spectrum . The numerical results for the functions are presented for and 0.16 in the form of universal curves representing as functions of the reduced impurity concentration . We have also established an upper limit to the reduced critical concentration for an arbitrary shape of α2F(ω)1. 相似文献
12.
B. Ghidini F. Navach A. Palano V. Picciarelli G. Zito J. Bröring K. Müller E. Paul W. Renneberg W. Rühmer J. Eades B. French L. Mandelli J. Moebes M.E. Edwards I. Smith R.A. Donald C. Palazzi-Cerrina 《Nuclear Physics B》1978,132(5):429-438
The reaction , where ps is a slow proton, was measured at 12 GeV/c incident momentum with the CERN-OMEGA spectrometer. Both antiproton and proton were identified uniquely by electronics information. We obtained 1844 events with four-momentum Transfer squared in the range 0.13 ? |t| ? 0.33 GeV2 and with invariant masses up to 2.5 GeV. The corresponding cross section in this t range is determined to be σ = 4 ± 0.4 μb. Extrapolating the differential cross section over the whole t range assuming dσ/dt ≈ exp(5.3t) we estimate a cross section of σ = 9.3 ± 2.0 μb. Comparison with data on (where ns is a slow neutron) in the same t range shows that the cross sections have approximately the same magnitude. 相似文献
13.
Differential cross sections were measured for the reactions for angles ranging from θlab = 6° to 48°. Optical-model analysis was performed for elastic α-scattering from 9Be at Eα = 48, 65 and 104 MeV, and DWBA and CC calculations were done for the inelastic α-scattering at Eα = 65 MeV. DWBA calculations for the 9Be(α, 3He) reactions do not fit the transfer data so well and extracted spectroscopic factors are in disagreement with those of Cohen and Kurath and with values obtained from other reactions. Full CRC calculations assuming a band structure for the low-lying states of 10B and employing a modified set of Cohen and Kurath spectroscopic factors yield globally better fits both in shape and in absolute cross section for differential cross sections to low-lying states in 10B obtained in 9Be(α, t)10B at . In general, strong coupled-channel effects mainly affecting the distorted waves are observed both in entrance and exit channels. 相似文献
14.
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
15.
We construct a nine-parameter family of π0π0 → π0π0 amplitudes F(s, t) such that (i) all the analyticity and unitarity conditions used in the derivation bounds are satisfied; (ii) F(s, t) can assume negative values in the unphysical region. Within this set, we minimize the values of and of the scattering length a00 = F(4, 0). Our best results are , whereas the best present lowers bounds are . 相似文献
16.
R. Gatto 《Physics letters. [Part B]》1974,51(4):371-375
If the hadronic contribution to vacuum polarization, which is proportional to the ration of e+e? annihilation into hadrons to that into μ+μ? rises asymptotically as a power of the squared four-momentum, the ratio point is bound to be less than and this limit is approached sooner for higher β. Other models of vacuum polarizations are also considered together with their possible origin and implications. 相似文献
17.
We prove that the generalized eigenfunctions of the Schrödinger operator are continuous for potentials obeing the following assumptions: V=V+?V?,V±≥0,, ,. 相似文献
18.
K. Siwek-Wilczynska E.H.du Marchie van Voorthuysen J. van Popta R.H. Siemssen J. Wilczynski 《Nuclear Physics A》1979,330(1):150-172
The mechanism of the production of fast α-particles in 12C induced reactions was studied over a wide range of bombarding energies (7.5–16.7 MeV/A) by measuring α-γ coincidences. Absolute cross sections for reactions, as well as inclusive α-particle production cross sections, have been determined. Depending on the bombarding energy, a fraction of 0.2–0.4 of the singles α-particles can be explained as resulting from incomplete fusion reactions (12C, α) and (12C, 2α) which correspond to a capture of “8Be” and “4He”, respectively. The remaining fragments of the projectile have, on the average, the beam-velocity energies and their angular distributions are forward peaked. Distributions of side-feeding to the yrast bands in the target-residue nuclei indicate that low partial waves are strongly hindered in the incomplete fusion reactions. The energy dependence of the cross sections for (12C, α) and (12C, 2α) incomplete fusion as well as for (12C, 3α) projectile breakup is given. A generalized concept of critical angular momentum which explains a competition between complete fusion, incomplete fusion and breakup reactions is proposed. 相似文献
19.
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