Nucleon Structure and Spin Effects in Elastic Hadron Scattering

Oleg Selyugin

doi:10.3390/sym13020164

Abstract

Soft diffraction phenomena in elastic nucleon scattering are considered from the viewpoint of the spin dependence of the interaction potential. Spin-dependent pomeron effects are analyzed for elastic pp scattering, and spin-dependent differential cross sections and spin correlation parameters are calculated. The spin correlation parameter AN is examined on the basis of experimental data from s=4.9 GeV up to 23.4GeV in the framework of the extended High Energy Generalized Structure (HEGS) model. It is shown that the existing experimental data of proton-proton and proton-antiproton elastic scattering at high energy in the region of the diffraction minimum and at large momentum transfer give the support of the existence of the energy-independent part of the hadron spin flip amplitude.

Highlights

Determination of the structure of the hadron scattering amplitude is an important task for both theory and experiment
The important property of Generalized parton distribution (GPD) consists in that they are tightly connected with the hadron form factors
The new High Energy Generalized Structure (HEGS) model gives a quantitative description of elastic nucleon scattering at high energy with a small number of fitting parameters

Summary

Introduction

Determination of the structure of the hadron scattering amplitude is an important task for both theory and experiment. There have been many observations of spin effects at high energies and at fixed momentum transfers [14,15]; several attempts to extract the spin-flip amplitude from the experimental data show that the ratio of spin-flip to spin-nonflip amplitudes can be non-negligible and may be independent of energy [16,17] It is generally believed, based on calculations of the simplest QCD diagrams, that the spin effects decrease as an inverse power of the center-of-mass energy and that the pomeron exchange does not lead to appreciable spin effects in the diffraction region at super-high energies. The model-dependent analysis based on all the existing experimental data of the spin-correlation parameters above pL ≥ 6 GeV allows us to determine the structure of the hadron spin-flip amplitude at high energies and to predict its behavior at superhigh energies [40] This analysis shows that the ratios Re φ5h(s, t)/( |t| Re φ1h(s, t)) and Im φ5h(s, t)/( |t| Im φ1h(s, t)) depend on s and t.

Coulomb-Nucleon Phase Factor

Nucleon Form Factors and GPDs

Extension of the HEGS Model with the Spin-Flip Amplitude

Findings

Conclusions