The six-quark-admixture in the form factor of the3He at large transfer momenta

Elastic form factor of the³He nucleus is analysed with the use of Gaussian-type and realistic nuclear wave functions with a contribution of six-quark admixtures taken into account. The latter has been chosen so as to describe the data of analysis of cumulative and other processes and it amounts to about 8%. It is shown that unlike the deuteron form factor for³He the quark-nucleon interference is essential. The six-quark admixture does not remove the second minimum in the form factor of³He as a three-nucleon system atq ²~50 fm^?2. The comparison with other theoretical models and available experimental data is performed.     

Polarization in elastic eD-scattering at large transfer momenta and quark structure of the deuteron

It is shown that a small (5–8)% admixture of the six-quark component in the deuteron wave function which is to be introduced to describe elastic eD-scattering at large transfer momenta changes essentially the behaviour of the polarization tensorT ₂₀ and the ratioR of the vectorP _x to tensor polarizationP _xz compared to the models which do not take such admixtures into account. The corresponding experiments are emphasized to be important, which are aimed at testing the predictions of models including six-quark admixtures in the deuteron.     

Neutron scattering from superfluid 4He at very large momentum transfer

Measurements of inelastic neutron scattering from liquid ⁴He were performed at very large momentum transfer (about 150 Å⁻¹) using an eV spectrometer with a pulsed spallation neutron source. A difference in the scattered neutron spectrum measured at 1.2 and 2.5 K was observed for the first time within this momentum-transfer range.     

Relativistic corrections to electron scattering by 2H, 3He,and 4He

Relativistic corrections to the scattering of electrons by a nonrelativistic nucleus are calculated, using the method of Close and Copley, and Krajcik and Foldy. Particular attention is paid to the deuteron, ³He and ⁴He. It is found that these corrections are substantially the same as those calculated by F. Gross for the deuteron. The corrections to ³He have the effect of moving the diffraction minimum, as calculated in a nonrelativistic model, outward by as much as 0.32 fm^?2. Smaller corrections are found for ⁴He.     

Measurement of tensor polarization in elastic electron-deuteron scattering at large momentum transfer

Tensor polarization observables ( t(20), t(21), and t(22)) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)(2). The experiment was performed at the Jefferson Laboratory in Hall C using the electron High Momentum Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q2 the deuteron charge form factors G(C) and G(Q). They are in good agreement with relativistic calculations and disagree with perturbative QCD predictions.     

3He electron scattering sum rules

Electron scattering sum rules for³He are derived with a realistic ground-state wave function. The theoretical results are compared with the experimentally measured integrated cross sections.This work was supported in part by the U.S. National Science foundation. Submitted to the symposium Mesons and Light Nuclei, Liblice, Czechoslovakia, June 1981.     

Coulomb effects in polarization transfer in elastic antiproton and proton electron scattering at low energies

The influence of Coulomb distortion on the polarization transfer in elastic proton and antiproton electron scattering at low energies is calculated in a distorted-wave Born approximation. For antiproton electron scattering Coulomb effects reduce substantially the polarization transfer cross-section compared to the plane-wave Born approximation, whereas for proton electron scattering they lead to a dramatic increase for kinetic proton lab energies below about 20keV.     

Nucleon momentum distributions in2H and3He from exclusive and inclusivey-scaling electron scattering

The possibility of obtaining information on nucleon momentum distributions in few-body systems by a coherent analysis of exclusive and inclusive electron scattering is discussed using the concept ofy-scaling.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.     

Polarized parity violating electron scattering on 3He

We calculate the asymmetry parameters, A, and figures-of-merit for polarized parity violating electron scattering from ³He via the reaction, e⁻ +³ He → e⁻ +³ He. We do this explicitly forv incident electron energies of 1.0 GeV and 4.0 GeV. We find a sharp and unexpected variation in A due to cancellations between the weak and electromagnetic form factors caused by the different q² dependences of these form factors. We find that at small angles, the asymmetry may be obtained to reasonably high accuracy for all energies considered and that the interesting region where the asymmetry has its first maximum and minimum is accessible for electron energies of 1 GeV or higher. In addition we find that the asymmetry and figures-of-merit are in the range of those for other proposed target nuclei. We also consider the possibility of strange quark contributions to the asymmetry and show that at the first maxima and minima, possible contributions of the strange quark current vector form factors cause large variations in the asymmetry which might be observed.     

Nearside-farside analysis of elastic scattering of polarized 3He

An exact decomposition of the scattering amplitudes into the nearside and farside components has been performed for the elastic scattering of 33 MeV ³He particles by nuclei. Calculations have been carried out for ⁴⁰Ca, ⁵⁴Fe, ⁸⁹Y, ^90,91Zr, ^207,208Pb and ²⁰⁹Bi and compared with the available cross section and polarization data. In particular the behaviour of the vector analysing powers is examined. Calculations of the interference between the nearside and farside components demonstrate that the interference plays a significant role in certain mass/energy regions. Regions where the scattering is dominated by the nearside component are discussed.     

Microscopic spin-orbit potentials for polarized 3He elastic scattering

The M3Y double folding model is used to calculate real central and spin-orbit potentials for ³He elastic scattering. These potentials are used to fit cross sections and analysing powers at 33 MeV for targets ranging from ¹⁶O to ⁵⁸Ni. The real central potential needs a normalization factor of about 0.85, but no change in the strength of the spin-orbit potential is necessary. Comparison is made with phenomenological and other microscopic studies of ³He elastic scattering.     

Generator-coordinate study of 3He+3He elastic scattering with a semirealistic nucleon-nucleon potential

The elastic scattering of ³He by ³He is studied in the framework of the generator coordinate method, using a new semirealistic nucleon-nucleon potential. All components of this potential have a soft core in the sense that they can be used in calculations where short-range correlations between nucleons are not taken into account. With this potential, a good agreement between calculated and measured cross sections and polarizations is obtained. The tensor component of the potential is found to be essential to explain the J-dependence of the empirical phase shifts, although the calculated polarizations are insensitive to the strength of the tensor potential.     

Non-energy weighted electron scattering sum rules for 3He

Electron scattering sum rules for ³He are derived with a realistic ground-state wave function. The theoretical results are compared with the experimentally measured integrated cross sections.     

The transverse electron scattering response function of 3He

Results on the transverse response function R _T (q,ω) of ³He obtained within the Lorentz integral transform [LIT] [1] method are presented. The response is calculated using the BonnRA nucleon-nucleon potential [2], the Tucson-Melbourne [3] three-body force, and the Coulomb potential for various momentum transfers. The results are compared with available data.