Electron-nucleon interaction in quasi-free scattering: (I). Non-relativistic Hamiltonian through second order

In the frame of a program aiming at examining the approximations involved in the theoretical treatment of (e, e′p) reactions, the electron-nucleon interaction producing the knock-out mechanism is considered in the non-relativistic approach of McVoy and Van Hove and compared with the relativistic one based on the one-photon-exchange Feynman graph. In this paper the non-relativistic Hamiltonian through second order in the nucleon recoil velocity is adopted; in the next paper higher order terms are included. The two approaches appear equivalent as far as the usual DWIA cross section is concerned, where a factorization occurs between the electron-nucleon cross section and the nucleon momentum distribution. However the unfactorized DWIA cross section behaves differently. This is attributed to a different off-shell behaviour of the two scattering amplitudes.     

Tensor interaction in heavy-ion scattering: (II). Partial-wave expansions

The turning-point-model relations between components of rank-2 tensor analysing power in polarized heavy-ion scattering, which were derived semi-classically in our previous work, are re-derived quantum-mechanically without resorting to any classical concept. Using partial-wave expansions of the scattering amplitudes, the turning-point-model relation is reduced to a relation between the diagonal and off-diagonal components of the tensor scattering amplitude for each type of tensor interaction (T_R, T_P and T_L). Numerical investigations and analytical investigations using a plane-wave expansion method show that these relations arise from universal features of heavy-ion scattering: large angular momenta and the short-range nature of the tensor potentials. An interrelation between the three types of tensor interaction is also obtained for each partial wave.     

Effective polarization in quasi-free scattering

A simple relation, involving only experimental quantities, for the effective polarizations in quasi-free (p, 2p) scattering on closed shell nuclei is tested for recent TRIUMF (p, 2p) experiments with 200 MeV polarized protons.     

Relativistic corrections to electron scattering: (II). Inelastic scattering

Relativistic corrections to inelastic electron scattering have been investigated using the results of a previous calculation on elastic scattering. A detailed discussion is made of the kinematics of inelastic scattering. Excitation of discrete states is treated in detail by two different methods, with particular attention paid to kinematical factors. Deuteron breakup is discussed and treated in a very similar manner to the discrete excitations. Comparison is made with analyses using plane wave final states and with previous work.     

Hyperon-nucleon scattering (II). Anomalous thresholds

We calculate the discontinuities across the anomalous cuts in the s-channel of ΣN → ΣN and ΣN → ΛN, using (i) the method of analytic continuation of m_Σ² in the unitarity formula due to Mandelstam and Gribov, and (ii) the Cutcosky rule. The result should be useful for a more rigorous treatment of hyperon-nucleon scattering in the low-energy region, in particular, for the N/D formalism in the presence of anomalous thresholds.     

Tensor interaction in heavy-ion scattering: (I). The turning-point model

The Heidelberg shape-effect model for heavy-ion tensor interactions is reformulated and generalized using the Hooton-Johnson formulation. The generalized semiclassical model (the turning-point model) predicts that the components of the tensor analysing power $\text{T}{}_{\mathrm{2q}}$ have certain relations with each other for each type of tensor interaction (T_R, T_P and T_L types). The predicted relations between the $\text{T}{}_{\mathrm{2q}}$ are very simple and have a direct connection with the properties of the tensor interaction at the turning point. The model predictions are satisfied in quantum-mechanical calculations for ⁷Li and ²³Na elastic scattering from ⁵⁸Ni in the Fresnel-diffraction energy region. As a consequence of this model, it becomes possible to single out effects from a T_P? or T_L-type tensor interaction in polarized heavy-ion scattering. The presence of a T_P-type tensor interaction is suggested by measured $\text{T}{}_{20}\text{/}\text{T}{}_{22}$ ratios for ⁷Li+⁵⁸Ni scattering. In the turning-point model the three types of tensor operator are not independent, and this is found to be true also in a quantum-mechanical calculation. The model also predicts relations between the components of higher-rank tensor analysing power in the presence of a higher-rank tensor interaction. The rank-3 tensor case is discussed in detail.     

Hadron scattering in two-dimensional QCD: (I). Formalism and leading order calculations

Two-dimensional quantum chromodynamics in the 1/N_c expansion is explored as a model for hadronic interactions. In meson-meson scattering, order 1/N_c terms exhibit embryonic “Regge” behaviour, with the crossed channel factorization, signature and exchange degeneracy properties found in dual Regge models. “Regge” intercepts are additive in the quark quantum numbers exchanged, and have a lower limit for large quark masses. Residues also factorize in the direct channel. An analogue for fixed angle scattering is presented which has deviations from dimensional counting rules related to form factors and Regge intercepts.     

Phenomenology of asymptotically free theories in deep inelastic scattering: (II). Neutrino scattering

The current neutrino inelastic charged current scattering data are shown to be in reasonable agreement with the predictions of simple four-flavour quark models with parameters determined from electroproduction. The data is consistent with the scale-breaking effects from asymptotic freedom that are included in the calculations. We discuss the uncertainty in the neutrino predictions coming from different parametrizations of electroproduction, the ambiguous extrapolation of the theory to low Q² and the effects of a non-zero value of R = σ_L/σ_T.     

Space-time structure of weak neutral currents: (II). Elastic scattering

The elastic scattering of neutrinos and antineutrinos on nucleons in which the initial and final nucleon polarizations are measured, is studied from the point of view of the space-time properties of the currents. Structure functions are defined and experimentally measurable quantities which can be usual to disentangle the Lorentz structure of the currents are given. Second class current effects are also examined.     

Spin-orbit distortion of the emerging nucleon in quasi-free electron scattering

Spin-orbit distortion of the emerging nucleon in quasi-free electron scattering is considered in the frame of a program aiming at examining the approximations involved in the theoretical treatment. The imaginary part of the spin-orbit coupling in the optical-model potential felt by the knocked out nucleon appears here to have a significant role. Its consequences in the case of the reaction ¹²C(e, e′p)¹¹B are discussed.     

Effects on squeezing and sub-poissonian of light in fourth harmonic generation up to first-order Hamiltonian interaction

The effects on squeezing and sub-poissonian of light in fourth harmonic generation (FHG) are investigated based on the fully quantum mechanically up to the first order Hamiltonian interaction in gt, where g is the coupling constant between the modes per second and t is the interaction time between the waves during the process in a nonlinear medium. FHG is a process in which an incident laser beam of the fundamental frequency ω interacts with a nonlinear medium to produce the harmonic frequency at 4ω. The coupled Heisenberg equations of motion involving real and imaginary parts of the quadrature operators are established. The occurrence of amplitude squeezing effects in both the quadratures of the radiation field in the fundamental mode is investigated and found to be dependent on the selective phase values of the field amplitude. The photon statistics of the pump mode in this process have also been investigated and found to be sub-poissonian in nature. It is found that there is no possibility to produce squeezed light in the harmonic mode up to first-order interaction in gt. Further, we have found the case up to second-order Hamiltonian interaction in gt that the normal squeezing in the harmonic mode is directly depends upon the fourth-order squeezing of the initial pump field. This gives a method of converting higher-order (fourth-order) squeezing into normal squeezing in the harmonic mode and vice versa.     

Parity non-conservation in low energy scattering of nucleons by light nuclei: (II). Results

The analysis developed in the preceding paper is applied to the low energy scattering of longitudinally polarized nucleons by ²H, ³He and ⁴He and of deuterons by ¹H. The sensitivity of the parity non-conserving asymmetry of the total cross section to the weak interaction is probed. The asymmetry is computed for various parity non-conserving nucleon-nucleon potentials in a distorted wave approximation. The asymmetries generally are found to depend sensitively on the parameters of the potential, but are smaller than those predicted for nucleon-nucleon scattering at the same energy.     

Large-angle scattering of heavy ions: (II). General structure of inelastic cross section

Closed-form expressions are derived for the differential cross section of inelastic heavy-ion scattering at large angles. The inelastic transition amplitude given by the distorted-waves theory for excitation of low-lying collective states is evaluated by an extension of analytic methods developed in the preceding paper for elastic large-angle scattering. The very close relation between the inelastic and elastic cross sections is displayed. In particular it is shown that the angular distributions have a universal form, and that the backward-angle inelastic excitation function has, aside from a slowly varying overall energy dependence, an oscillatory gross structure of diffractive origin which is nearly identical to that of the elastic excitation function, irrespective of the physical mechanism involved.     

Inelastic proton scattering from deformed nuclei: (II). Results with a local approximation

We describe an approximate method of including exchange effects in proton inelastic scattering appropriate to situations where a coupled channel approach is essential, i.e. deformed nuclei. We demonstrate that in this approach the effects of exchange are not large, contrary to what is often said, provided consistence between elastic and inelastic scattering is maintained. The corrections may be roughly represented as a “shifted” zero range approximation which can be viewed as giving a rather smallL-dependent effect. The effect on the extraction of quadrupole moments should not exceed 4% and of hexadecapole moments 10% except at the lowest energies.     

On the lowest order electroweak corrections to spin-12 fermion scattering: (I). The one-loop diagrammar

Based on a gauge model of the electroweak interaction the total set of all one-loop diagrams for scattering of $\text{spin}\text{-}\text{1}\text{2}$ fermions is calculated. Throughout the calculations, the type of fermions (?, ν, …) and of heavy vector bosons (W^±Z⁰, …) is not specified. Derivation of finite parts of each diagram is carried out under the restriction that all invariants of the amplitude are much larger than all fermion masses squared. This allows us to use the expression obtained at arbitrary high energies where weak and electromagnetic interaction strengths are comparable.     

随机粗糙面激光脉冲散射四阶统计特征

依据基尔霍夫近似,推导出一维高斯随机粗糙面四阶统计特性解析式,并获得脉冲波入射下粗糙面双点双频四阶矩互相关函数.数值计算不同入射角,不同高度起伏和相干长度,随机粗糙面双点双频四阶矩互相关函数随相干频谱带宽频差,散射角的变化情况.计算结果表明,高度起伏和相干长度对粗糙面散射四阶统计特的影响很大,粗糙面越光滑,在镜反射方向有最大的四阶矩散射峰值和小的相关带宽.随着粗糙度增加,随机粗糙面脉冲散射的四阶矩的相干分量减弱,展宽现象明显;而相干带宽频差越大,四阶矩衰减越快. 关键词： 四阶矩统计特征 双点双频互相关函数 随机粗糙面 脉冲波散射     

7Li quasi-free scattering off the α-cluster in 9Be nucleus

Spectra of coincident charged particles from the reactions induced by a 52 MeV ⁷Li beam incident on a beryllium target were measured. Strong contributions of the ⁷Li quasi-free scattering off the α-cluster in ⁹Be nucleus were observed. This observation supports the conclusions from the study of complete fusion of weakly bound light nuclei at low energies that the “fragility” of the nuclei makes their fusion less probable. Received: 1 June 1998     

Nucleon-alpha elastic scattering analyses: (II). 0 to 21 MeV energy-dependent n-α analysis

An energy-dependent phase-shift analysis of 0–21 MeV n-α scattering is presented and compared to the previous 0–23 MeV p-α analysis. The error matrix and inverse error matrix for both the n-α and the p-α analyses are given.     

Pole approximation in the quasi-free t + p scattering and the t(p,d)d reaction via the t + d interaction

The t(p,p)t and t(p,d)d channels have been investigated in an indirect way through the ²H(t,tp)n and ²H(t,dd)n three-body reactions performed at E _t = 35.5?MeV in quasi-free kinematics. The agreement with direct data supports the pole approximation at energies above the Coulomb barrier.