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1.
The effect of the nucleon recoil for the antikaon-deuteron scattering is investigated in the framework of the effective field theory. In particular, we concentrate on the calculation of the nucleon recoil effect for the double-scattering process. It is shown that the leading correction to the static term that emerges at order x1/2 \xi^{{1/2}}_{} with x \xi = M K/m N vanishes due to a complete cancellation of individually large contributions. The resulting recoil effect in this process is found to be of the order of 10-15% as compared to the static term. We also briefly discuss the application of the method in the calculations of the multiple-scattering diagrams.  相似文献   

2.
3.
In order to examine the validity of the impulse approximation for pion-nucleus scattering in the 33-resonance energy region, we consider pion-scattering from a “nucleus” which consists of a single nucleon bound in a harmonic oscillator potential. A separable πN interaction is assumed. The oscillator parameter is chosen such that the nuclear sizes are fitted for 4He ~ 16O. The binding effect is found to result in a downward shift of the resonance energy (by about 20 MeV), and an increase (by 50 ~ 70%) of the total cross section near the resonance. The angular distribution is also strongly modified. In connection with the binding effect, the importance of a careful treatment of nucleon recoil is emphasized. It is pointed out that the closure approximation which is often used to sum over intermediate nuclear states leads to very misleading results. The effect of the Pauli principle is also examined by excluding some intermediate states.  相似文献   

4.
5.
The effect of the inclusion of different models of three nucleon (3N) forces in p ? 3He elastic scattering at low energies is studied. Two models have been considered: one derived from effective field theory at next-to-next-to-leading order and one derived from a more phenomenological point of view—the so-called Illinois model. The four nucleon scattering observables are calculated using the Kohn variational principle and the hyperspherical harmonic technique and the results are compared with available experimental data. We have found that with the inclusion of both 3N force models the agreement with the experimental data is improved, in particular for the proton vector analyzing power A y .  相似文献   

6.
《Nuclear Physics A》1988,480(2):323-341
The differential cross sections for elastic scattering of 6,7Li from 12C and inelastic one from the lowest three excited states of 12C have been measured at bombarding energies of 18–28 MeV/nucleon. Theoretical analyses of the data have been performed in which consistent treatments of density distributions for the ground and excited states of both projectile and target nuclei are made in the framework of microscopic cluster models for 6,7Li and 12C and projectile-target interactions are generated by the double folding of the M3Y effective nucleon-nucleon interaction. About 25% reduction of the real part of folded potentials is required both in the analyses of elastic scattering with the single-channel calculation and in those of inelastic scattering with the coupled-channel calculation including the excited states of 12C. This reduction can be explained as a projectile breakup effect on elastic and inelastic scattering in comparison with a coupled-discretized-continuum-channels (CDCC) calculation and an extended CDCC one which allows mutual excitations of both projectile and target nuclei for 6Li case, respectively. It is also seen that an effect due to the target excitation on elastic scattering is of less importance than that of the 6,7Li projectile breakup processes even fora deformed nucleus like 12C. Discrepancy between the extended CDCC calculation and inelastic data for the 0+2 state of 12C suggests a strong influence from the 12C → 3α breakup channels in the 6Li case.  相似文献   

7.
The polarization of the recoil proton in πN-scattering has been calculated as a function of the scattering angle at the energies 150, 170, 190 MeV. It is shown that this polarization depends sensitively on the πN-scattering phase-shiftP 11. Slight changes of the other phase-shifts do not affect the polarization to the same extent. New measurements of the differential cross-section and of the polarization in the process π?+p→π?+p are suggested. They would allow for a new precise phase-shift analysis, which could possibly determine the sign of theP 11-phase at the inelastic threshold. This sign is important in connection with the bound-state picture of the nucleon.  相似文献   

8.
The customary deformed-hard-sphere method of calculating the Coulomb excitation term in inelastic scattering of α-particles from deformed nuclei is shown to be inadequate. An exact double folding calculation which eliminates the ambiguity in choice of Coulomb radius results in a change in the extracted β2 for 154Sm from 0.225 to 0.26. This work has possible implications for a wide range of heavy ion scattering which deserve exploration.  相似文献   

9.
A singles measurement of the quasielastic scattering of 255 MeV pions by 27Al and 208Pb has been made. The measured values for the ratio R of π+ and π? induced cross section, averaged over all measured angles of 2.2 ± 0.2 and 1.5 ± 0.1 for 27Al and 208Pb respectively are substantially below the classical impulse approximation value of 11. A semiclassical nucleon charge exchange model is described for singles and coincidence measurements and is compared with the measured proton spectra. The comparison indicates that the singles proton spectra are dominated by events other than the quasielastic process whereas the coincidence data reported earlier and compared with the present calculations support the quasielastic interpretation. A strongly decreasing dependence of R on A for coincidence measurements may be interpreted as supporting the view that recoil nucleon charge exchange plays an important role in the quasielastic knockout process.  相似文献   

10.
New short baseline neutrino experiments open new possibilities of high precision study of different neutrino processes. We present here results of the calculation of the polarization of final nucleon in elastic NC $\nu _\mu (\bar \nu _\mu )$ -nucleon scattering. In a numerical analysis the sensitivity to the different choices of the axial and axial strange form factors is examined. Measurements of the polarization of the final proton in elastic e-p scattering drastically changed our knowledge about the electromagnetic form factors of the proton. From measurement of the nucleon polarization in the NC elastic scattering a new additional information about the axial G A (Q 2) and the strange axial G s A (Q 2) form factors of the nucleon could be inferred.  相似文献   

11.
We present a theoretical analysis of a broad range of aspects of intermediate energy nucleon-deuteron scattering. This analysis is based on a multiple scattering approach using knowledge of the deuteron's structure and nucleon-nucleon interactions. Conversely, comparison of this theory with experiment can yield information about low and intermediate energy strong interactions. The relationship of this multiple scattering type of approach to the complementary Faddeev equation approach is discussed. Our program consists of calculating the single scattering and one nucleon exchange contributions in a realistic way then parametrizing the remaining contributions as an S-wave. We argue that the largest error in this analysis is the P-wave part of the double scattering and we give estimates of its size. The single scattering integral is evaluated numerically. Coulomb effects are neglected. We derive the relativistic expressions for single scattering and nucleon exchange and discuss the approximations made, including the off-mass-shell extrapolation of the nucleon-nucleon scattering amplitude. Fits are made to experimental measurements of differential cross sections, nucleon polarizations, and total elastic cross sections. Unitarity is maintained. We tabulate the partial waves for J ? 52, L ? 2. They are consistent with recent Faddeev calculations. We argue that with the additional calculation of double scattering the deuteron D-state percentage can be determined to the same relative uncertainty as the differential cross section. Even without the calculation of double scattering, our results indicate a D-state percentage around 8%. In an effort to provide benchmarks for future work, we have tried to be conscientious in describing our techniques and in tabulating numerical results. Comparisons are also made with earlier analyses.  相似文献   

12.
It is shown that, under kinematical conditions of quasielastic knockout, the differential cross section for the exclusive process p(e, e′π +)n induced by longitudinal virtual photons γ* L changes its physical nature as the recoil momentum |k| of the spectator nucleon grows from values in the range |k| ~ 0.1–0.4 GeV/c, which are typical in studying the pion cloud of the nucleon, to values around |k| ~ 1 GeV/c. Calculations within the 3 P 0 quark microscopic model reveal that the amplitudes for the deexcitation of vector and pseudovector mesons via the processes ρ + + γ* L π + and b 1 + + γ* L π + become dominant here. Concurrently, the effective momentum distributions develop a substantial angular anisotropy of about 50% with respect to the angle between the momentum of the photon γ* L and the recoil momentum of the spectator nucleon, the longitudinal differential cross sections undergoing respective changes. In this region, the energy of knock-on pions is expected to be about 5 GeV under conditions of quasilastic kinematics.  相似文献   

13.
We present moments (both ordinary and Nachtmann) of the nucleon valence structure function measured in high Q2νFE scattering, supplemented by data from deep inelastic eD scattering. These data seem to agree with QCD predictions for vector gluons. The QCD parameter Λ is found to be of the order 0.5 GeV.  相似文献   

14.
A new investigation of the inelastic electon scattering from proton in the O(4, 2) models is presented. The resultant explicit structure functions in the limit satisfy scaling, F1(ξ) ≠ 0 (σT ≠ 0), the Drell-Yan relation F2(ξ) ~ (1?ξ)3 and, approximately, the Callan-Gross relation F2(ξ) ≈ 2ξF1(ξ).  相似文献   

15.
Experimental indications that there exists single-stage fission of 238U and 232Th nuclei that is induced by a nearly transverse flux of intranuclear nucleons are obtained from an experiment that employs a two-arm time-of-flight spectrometer exposed to a beam of 1-GeV protons. A nearly transverse flux of mean multiplicity about 10 to 15 nucleons is initiated by a recoil nucleon of mean momentum about 240 MeV/c in the quasielastic scattering of an incident proton.  相似文献   

16.
The dd3 Hen reaction is considered at the energies between 200 and 520?MeV. The Alt–Grassberger–Sandhas equations are iterated up to the lowest order terms over the nucleon–nucleon t-matrix. The parameterized 3 He wave function including five components is used. The angular dependence of the differential cross section and energy dependence of tensor analyzing power T 20 at the zero scattering angle are presented in comparison with the experimental data.  相似文献   

17.
We present a theoretical treatment of the pion-deuteron system, meant specifically for the energy region below 100 MeV, and based on the Faddeev method for three-body scattering. This includes all orders of multiple scattering, two- and three-body unitarity (to a good approximation), nucleon recoil, deuteron d-state and a correct treatment of spin and isospin. For consistency with nuclear physics we treat the nucleons non-relativistically. However, relativistic kinematics are used for the pion. In order to obtain one-dimensional integral equations in the three-body system, we have constructed a set of separable πN t-matrices (with analytic form factors), which fit selected data up to 300 MeV. A comparison is made with existing π+d data at 48 MeV. This data tends to favour the Faddeev type of energy dependence for the πN t-matrix in the πd system. This could also be important in low-energy pion-nucleus scattering.  相似文献   

18.
Naively, the “best” method of renormalization is the one where a momentum cutoff is taken to infinity while maintaining stable results due to a cutoff-dependent adjustment of counterterms. We have applied this renormalization method in the non-perturbative calculation of phase-shifts for nucleon–nucleon (NN) scattering using chiral NN potentials up to next-to-next-to-next-to-leading order (N3LO). For lower partial waves, we find that there is either no convergence with increasing order or, if convergence occurs, the results do not always converge to the empirical values. For higher partial waves, we always observe convergence to the empirical phase shifts (except for the 3G5 state). Furthermore, no matter what the order is, one can use only one or no counterterm per partial wave, creating a rather erratic scheme of power counting that does not allow for a systematic order-by-order improvement of the predictions. The conclusion is that infinite-cutoff renormalization is inappropriate for chiral NN interactions, which should not come as a surprise, since the chiral effective field theory (chiral EFT), these interactions are based upon, is designed for momenta below the chiral-symmetry breaking scale of about 1 GeV. Therefore, this value for the hard scale should also be perceived as the appropriate upper limit for the momentum cutoff.  相似文献   

19.
Along the line of a previous work we calculate the π+?P radiative scattering cross section at the incoming π+ energies of Tπ = 298, 269, and 324 MeV. The results of the calculation turn out to be in very good agreement with the experimental data for all the energies, showing the great importance of the rescattering and recoil corrections given by the proton motion.  相似文献   

20.
罗辽复  徐行 《物理学报》1962,18(6):291-297
本文用塔姆-唐可夫近似解K+介子和核子的弹性散射问题,得到了K介子实验室动能400Mev以下的相移截面和能量的关系,并和实验及前人的理论结果作了比较。计算中较严格考虑了核子反冲效应,指出了在考虑了反冲效应后能使理论曲线在高能端更与实验曲线接近。同时就Λ-K和∑-K的各种可能的宇称情况进行了分析,排斥了相对宇称皆正的可能,并指出Λ-K和∑-K的相对宇称选取不同的符号和二者皆取负号一样,能符合K+-p散射实验,但在分析K+-n散射时仍遇到困难。  相似文献   

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