Measurement of the transverse beam spin asymmetry in elastic electron-proton scattering and the inelastic contribution to the imaginary part of the two-photon exchange amplitude

We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A( perpendicular), at two Q2 values of 0.106 and 0.230 (GeV/c)(2) and a scattering angle of 30 degrees 相似文献   

Pion-nucleon backward scattering: The location of the amplitude zeros

The complex zero trajectories for the πN helicity amplitudes with definite u-channel isospin are determined from phase shifts. Some of these trajectories display systematic behaviour, having fixed values of (u?u₀), where u₀ corresponds to the backward direction, and small values of Im u. On the assumption that this systematic behaviour will persist to higher energies one can make predictions about the locations of zeros in these helicity amplitudes at high energies. These zero locations are very relevant to an understanding of the mechanisms involved in πN backward scattering. The results, which show quite a striking pattern for the zero positions in the various amplitudes, are discussed from the point of view (a) of the experimental data for πN backward scattering and (b) of a theoretical interpretation of the interaction mechanism.     

Structure of the antiproton-proton elastic scattering amplitude

It is found that the simple expression [(πcq)/sinh(πcq)][J ₁(Rq)/(Rq)] for the elastic scattering amplitude makes it possible to well describe differential cross sections over a broad range of energies from 100 MeV to \(\sqrt s \) = 1800 GeV. This parametrization can be used to calculate antiproton-nucleus and antinucleus-nucleus amplitudes and cross sections, which are necessary in accelerator experiments and in cosmic ray physics. The generalization of the wavelet expansion to the case of functions defined on a semi-infinite interval is also proposed.     

Ratios of the real to imaginary part of the p 4He and pn elastic scattering amplitudes at 0.7 GeV

The ratios ρ _p He and ρ _pn of the real to imaginary part of the forward proton-⁴He and proton-neutron elastic scattering amplitudes have been determined from the data on proton-helium elastic scattering cross sections at 0.7 GeV in the Coulomb-nuclear interference region to be ρ _p He =?0.06±0.06 and ρ _pn = ?0.28±0.12. The existing experimental values of ρ _p He are compared in a wide range of energies with the corresponding values calculated by means of the Glauber model using the ratios ρ _pp and ρ _pn evaluated with the help of the dispersion relations.     

Peculiarities of the amplitude of elastic subbarrier impurity scattering

A formula for the amplitude of electron elastic subbarrier (in the domain of imaginary momenta) scattering by an impurity modeled as a spherical potential well is derived. An equation is obtained to find the features (poles) of this amplitude in a complex energy plane in the close vicinity of which the energy spectrum of quantum resonant percolation trajectories in M-I-M contacts (M = N (normal metal) or S (superconductor) and I is an insulator) with weak (low impurity concentration) structural disorder in the I layer is concentrated [1–4].     

Measurement of the real part of the forward scattering amplitude in K±p elastic scattering at 10.4 and 14 GeV/c

The differential cross section for K^±p elastic scattering has been measured in the very low t region (0.003 < t < 0.2 GeV²) in a wire chamber spectrometer experiment at 10.4 and 14 GeV/c. The interference effect observed between the Coulomb and the nuclear interaction has been used to determine α, the ratio of real to imaginary part of the forward scattering amplitude. At 10.4 GeV/c we measure α(K⁺p) = ?0.21 ± 0.06 and α(K^?p = 0.08 ± 0.04, and at 14 GeV/c, α(K⁺p) = ? 0.13 ± 0.03 and α(K^?p) = 0.000 ± 0.04 in agreeement with the predictions of dispersion theory calculation.     

The imaginary part of the helicity nonflip C = −1 exchange amplitudes in elastic scattering between 6 and 14 GeV

Using accurate data on the differential cross sections for elastic scattering of particles and antiparticles on protons from 6 to 14 GeV, the projection of the C = ?1 exchange amplitude onto the dominant diffractive amplitude is measured. Strong peripherality in impact parameter space is observed for all the measured amplitudes with peak values scaling with the interaction radius. The zero of the imaginary part of the C = ?1 exchange amplitude in K^±p scattering moves to smaller t values as the energy increases from 6 to 14 GeV. The p^±p exchange amplitude is more peripheral than the π^±p and K^±p counterparts and an unexpected energy dependence is observed.     

High-energy elastic scattering amplitude of unpolarized and charged hadrons

Zeitschrift für Physik C Particles and Fields - Electromagnetic as well as strong interactions play a significant role in the elastic scattering of unpolarized charged hadrons. One can...     

Bounds on the elastic scattering amplitude at finite energies

A bound on the ratio of differential cross sections of particle and antiparticle at finite energies has been derived using the relation between phase and modulus of the scattering amplitude which follows from analyticity, unitarity and crossing symmetry.Presented by Yu. S.Vernov at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975.     

On the real part of the amplitude of elastic scattering of proton on deuteron at an energy of 8 GeV

The elastic scattering of a proton on a deuteron at an energy of 8 GeV is studied by the method of multiple transitions of protons through a target 1·5 μ thick, made from (CD ₂)_n. Altogether 27,385 reflected deuterons were recorded and measured by means of nuclear emulsions. From an analysis of the course of the differential cross-section as a function of the scattering angle in the limits of 1·4° to 8·9° (¦t¦= 0·0042 – 0·1750 (GeV/c)²) we determined the ratio of the real and imaginary parts of the scattering amplitude

$$\alpha = \frac{{\operatorname{Re} A(0)}}{{\operatorname{Im} A(0)}} = - 0 \cdot 36 \pm 0 \cdot 08$$     

Physical meaning of the phase of high energy elastic scattering amplitude

The influence of the phaset-dependence on the profiles of high energy elastic hadron scattering in the impact-parameter plane are discussed. The analysis of interference experimental data concerning pp, ¯pp and p⁴He scattering is summarized. It is shown that in all these cases the high-energy elastic scattering can be interpreted as a peripheral process.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday.     

Approximate construction of the scattering amplitude from Mandelstam representation and elastic unitarity

An approximate expression for the scattering amplitude is derived from the Mandelstam representation and the elastic unitarity. To demonstrate our procedure in the relativistic case we considerπ-N scattering, omitting spin and isospin for simplicity. Non-relativistic potential scattering is discussed in detail.     

Dispersion relation for elastic electron-hydrogen atom forward scattering amplitude

The elastic e + H forward scattering amplitude is an analytical function in the complex energy E plane and has two cuts on the real axis: 0 < E < ∞ and ?∞ < E < ?B, B being the hydrogen ionization potential. The e+H dispersion relation contains two integrals over the right and left cuts.     

Measurement of the real part of the forward scattering amplitude in K±p elastic scattering between 0.9 and 2.6 GeV/c

The differential cross section for K^±p elastic scattering has been measured in the forward meson direction (0.0008 < t < 0.1 GeV²) in an electronics experiment at incident momenta between 0.9 and 2.06 GeV/c. The high statistics and absolute normalisation of the data allow a good determination of the real part of the forward nuclear scattering amplitude by means of the Coulomb-nuclear interference effect.     

Algebraic structure of the amplitude of elastic scattering by a two-dimensional crystal

The coherent scattering of spin-S particles by a monatomic crystal film is considered, with rescattering taken into account. A relation between the amplitudes q_j of different diffraction orders and the dielectric tensor () of the two-dimensional crystal is found. The relation can be used to obtain () for an arbitrary frequency (including resonant frequencies) in terms of elastic scattering data. The possibility of bound states of the particles in the monatomic film is demonstrated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 30–34, April, 1987.The author thanks V. L. Vinetskii for interest in the work and for useful discussions.