On the polarization of the final nucleon in NC elastic \nu _\mu (\bar \nu _\mu )-N scattering

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.     

Polarization in quasielastic (p,2p) scattering on a 4He nucleus at 1 GeV

The polarization of secondary protons from the (p, 2p) reaction induced by 1-GeV protons incident to a ⁴He nucleus was measured in a kinematically complete experiment. By using a two-arm magnetic spectrometer, two secondary protons from this reaction were recorded in coincidence at unequal scattering angles of Θ₁ = 18°?24.21° and Θ₂ = 53.22° over a broad range of the recoil-nucleus momentum K _B between 0 and 150 MeV/c. It was found that the measured polarization of either secondary proton is less than that observed in free elastic proton-proton scattering. The magnitude of this difference is determined by the mean binding energy of s-shell protons rather than by the effective nuclear density. The polarizations measured in inclusive quasielastic and elastic scattering of 1-GeV protons on ⁴He nuclei are presented for scattering angles in the range Θ₁ = 18° ? 24.21°.     

Elastic and inelastic scattering of 178 MeV protons from 58Ni and 60Ni

The elastic and inelastic scattering of 178 MeV protons from ⁵⁸Ni and ⁶⁰Ni has been studied. Angular distributions were measured for the differential cross sections for elastic scattering as well as inelastic scattering from excited states below about 5 MeV, all with natural parity. For the elastic and for the inelastic scattering from the first excited state (2⁺ in both nuclei, the angular distributions for the polarization were also measured. The measurements extend out to c.m. angles of about 60°, corresponding to a momentum transfer of about 600 MeV/c.The elastic and inelastic scattering data were compared to the results of coupled-channel calculations in the vibrational model using a deformed spin-orbit interaction of the full Thomas form. Good agreement was found in general showing that the main features of the experimental results are well described in this model.     

Polarization in charge exchange reaction π−+p→π0+n at 40 GeV/c for the 4-momentum transfer range 0<|t|<2 (GeV/c)2

The results on measuring polarization in charge exchange reaction π^?+p→π⁰+n at 40 GeV/c are presented for the 4-momentum transfer range from 0 up to 2 (GeV/c)². At |t|≦0.4 (GeV/c)² the polarization has a positive sign. In the “crossover” region of π^± elastic scattering a possible minimum in the polarization behaviour has been seen for the first time. the polarization is zero within the statistical accuracy near this point. In the “deep” region of the charge-exchange differential cross-section the polarization has a negative sign. The presented data are not in agreement with the modern theoretical models.     

Elastic and inelastic scattering of 800-MeV protons on <Superscript>16</Superscript>O and <Superscript>20</Superscript>Ne nuclei

Differential cross sections and polarization observables for the elastic and inelastic scattering of 800-MeV protons on ¹⁶O and ²⁰Ne nuclei are calculated on the basis of the theory of multiple diffractive scattering and the α-cluster model involving dispersion. The single-particle nucleon-density distributions obtained within the α-cluster model involving dispersion are used in the calculations. The differential cross sections and polarization calculated for elastic and inelastic p¹⁶O and p²⁰Ne scattering are compatible with available experimental data. The spin-rotation functions calculated for elastic p¹⁶O and p²⁰Ne scattering within the independent-nucleon model differ qualitatively from their counterparts calculated within the α-cluster model involving dispersion.     

The antiproton-nucleus elastic scattering and the alpha-cluster model with dispersion

The elastic scattering differential cross sections of intermediate energy antiprotons on¹²C and¹⁶O nuclei and the elastic scattering polarization observables of antiprotons on these nuclei have been calculated on the basis of theα-cluster model with dispersion and multiple diffraction theory. The results of these calculations are compared with the experimental data.     

Polarisation und differentieller Wirkungsquerschnitt der Neutronen aus der Reaktion9Be(α,n)12C

The differential cross section and the angular distribution of the polarization of neutrons from the reaction⁹Be(α, n) leading to the ground state of¹²C have been determined at 1.75 and 1.96 MeV energy of theα-particles. The polarization was measured by left-right asymmetry induced by elastic scattering from⁴He. From Blatt, Biedenharn and Simon, Welton theory analysis a set of spectroscopic data has been obtained for five states of the compound nucleus¹³C.     

Scattering of He and He from polarized He between 7 and 18 MeV

Polarization analyzing power of ³He³He and ³He⁴He elastic scattering is reported for bombarding energies between 7.5 and 17.9 MeV. A phase-shift analysis for ³He⁴He elastic scattering incorporating this and other polarization data is presented. The analyzing power of ³He³He elastic scattering is consistent with zero at θ_c.m. = 66°.     

Elastic and inelastic scattering of protons from Li between 25 and 45 MeV

The elastic and inelastic scattering of protons from ⁶Li has been studied at incident energies of 25.9, 29.9, 35.0, 40.1 and 45.4 MeV. The 2.18 MeV (3⁺, T = 0) first excited state of ⁶Li was found to be strongly excited, but the 3.56 MeV (0⁺, T = 1) second excited state was quite weakly excited. Angular distributions for excitation of the 2.18 MeV level were measured at all five energies, while angular distributions for excitation of the 3.56 MeV level were extracted only at 25.9 and 45.4 MeV. To test the applicability of the optical model for the scattering of protons from such a light nucleus the elastic scattering angular distributions have been analyzed using the eleven-parameter search code SEEK. Available polarization angular distributions were included in the analysis. Reasonable fits to the data have been obtained with an average geometry potential. Theoretical estimates of the real part of the optical potential and the inelastic scattering differential cross sections have been made using the microscopic model for proton-nucleus scattering. Both phenomenological and realistic forces have been considered and the necessary nuclear transition densities have been extracted from experimental elastic and inelastic electron scattering data. An estimate of a possible spin-spin term in the optical potential has also been made.     

Polarization in proton-proton elastic scattering at 10, 14 and 17.5 GeV/c

Data on the polarization parameter in pp elastic scattering in the |t|-range from ∼0.1 to ∼ 2.9 (GeV/c)² and at 10, 14 and 17.5 GeV/c are presented.     

Fusion excitation function measurements for the 16O+58Ni and 16O+62Ni systems

High precision fusion excitation functions have been measured for the ¹⁶O+⁵⁸Ni and ¹⁶O+⁶²Ni systems from which fusion barrier distributions have been evaluated. Coupled-reaction-channels (CRC) calculations, which describe elastic and quasi-elastic scattering, also satisfactorily reproduce the fusion cross sections and barrier distributions. The small value of Z₁Z₂ in this case leads to barrier distributions with relatively little structure. However, in conjunction with the detailed elastic scattering data for these systems, this allows us to elucidate the role of previously ignored states in ¹⁶O in pushing the entire distribution to lower energies. These shifts are consistent with derived magnitudes of polarization potentials for both systems.     

Measurement of the polarization parameter in pp elastic scattering at 150 GeV/c

The polarization parameter in pp elastic scattering at 150 GeV/c, and in the momentum transfer interval 0.4 ? ?t ? 3.0 GeV², has been measured in an MWPC and scintillation counter experiment at the CERN SPS using a polarized proton target. The polarization is decreasing steadily from zero to ≈ ? 10% in the range 0.4 < ?t < 1.3 GeV²; for higher |t| the data suggests a change of sign. Results are also given for the differential cross section, which exhibits a small dip at ?t = (1.46 ± 0.01) GeV.     

Program of measurement of the asymmetry P at the minima of the differential cross section for elastic π + p scattering

A program of measurement of the polarization parameter P in elastic π ⁺ p interaction in the resonance region of backward pion scattering is presented. This program is aimed at determining the bifurcation points of the trajectory of zeros of the pion-nucleon amplitude and, hence, at unambiguously reconstructing the amplitude of πN scattering in the second resonance region. It is planned to perform a relevant experiment in a pion beam from the accelerator of the Institute of Experimental and Theoretical Physics (ITEP, Moscow).     

The short-range nucleon-nucleon repulsion

The short-range repulsion (0.2–0.4 fm) between nucleons is investigated. The opposing effects of ω-meson exchange and ε-meson (J^p = 0⁺) exchange are investigated, and the relation to Regge behaviour is demonstrated using fixed-s dispersion relations. The energy dependence of the short-range interaction is emphasized, and experimental data on polarization in elastic NN scattering at high energy are used to give the necessary coupling constant.     

Tensor interactions and polarization phenomena in heavy-ion scattering

Elastic and inelastic scattering of ⁷Li by ⁵⁸Ni at E_lab = 14.2 and 20.3 MeV is investigated theoretically, special emphasis being laid on polarization phenomena. A parameter-independent study shows second-rank tensor interactions to be the main origin of tensor analyzing powers for both elastic and inelastic scattering. Coupled-channel (CC) calculations using cluster-folding interactions which include the tensor terms are found to be successful in reproducing the data for cross sections and vector and tensor analyzing powers, when projectile excitation effects are sufficiently taken into account. Scattering of ⁶Li by ⁵⁸Ni at E_lab = 20.0 MeV is also investigated by the CC calculation, where successes similar to the ⁷Li case are obtained in understanding experimental data.     

Angular distributions of neutron polarization from the 14C(p,n)14N and 11B(α, n)14N reactions and R-matrix analysis oF 15N in the excitation-energy range between 11.5 and 12.5 MeV

Angular distributions of neutron polarization from the ¹⁴C(p, n)¹⁴N and ¹¹B(α, n)¹⁴N reactions have been studied for the particle energies E_p = 1.788, 2.025, 2.272 and 2.450 MeV, and E_α = 2.049 MeV. The polarization was derived from the left-right asymmetry induced by elastic scattering from ⁴He. Together with existing measurements of angular distributions and total cross sections for several reaction channels leading to ¹⁵N with an excitation energy between 11.5 and 12.5 MeV, these data were used to deduce from R-matrix analysis a set of resonance parameters for the ¹⁵N levels in this energy range.     

Electromagnetic corrections to the s-wave scattering lengths in pionic hydrogen

Motivated by the recently performed X-ray precision experiments on pionic hydrogen (preceding paper), we reconsider the problem of electromagnetic corrections to the π - N scattering lengths. Based on a relativistic two-channel approach, we find corrections to the π⁻p elastic and single-charge-exchange (SCE) scatering lengths due to the point-Coulomb interaction, the finite-size Coulomb interaction (including the pion size), the first-order vacuum polarization (Uehling potential) and the (π⁻p) - (π⁰n) mass difference (mass difference effect). We also estimate the contribution due to the (γ,n) decay channel. The total corrections to the elastic and the SCE scattering lengths are found to be δ_ε = −(2.1 ± 0.5) × 10⁻² and δ_Γ = −(1.3 ± 0.5) × 10⁻². Previously published values for the corrections are critically compared with our results.     

Measurement of the polarization parameter in small angle proton-proton elastic scattering at 6 GeV/c

The polarization parameter in pp elastic scattering was measured at 6 GeV/c with fine t resolution for 0.02 < ?t < 0.5 GeV² using a polarized proton beam with Effective Mass Spectrometer at the Zero Gradient Synchrotron. The polarization rises like √?t in the interval 0.02 < ?t < 0.1 GeV², No statistical significant structure was found in this region of momentum transfer.     

Phase shift analysis of the reaction K+N → KN below 1.6 GeV/c

An energy-dependent partial wave analysis was made for the K⁺ nucleon scattering in the energy range between 0.2 and 1.6 GeV/c using the data including our new polarization data of K⁺n elastic and charge-exchange scattering. Counterclockwise Argand plots were found for the partial waves P₁₃, P₀₁ and D₀₃.