From Diffraction In Classical Optics To Diffraction In High-energy Scattering

Nuclear science is concerned with the origin and structure of the core of the atom,the nucleus and the nucleons.Using Quantum Chromodynamics(QCD)as a theoretical tool,hi gh energy nuclear physics mainly computes various of high energy process,however the diffraction process in high energy scattering is one of the most significant processes.Especially electron-proton collisions in deep ineleastic scatter-ing(DIS)are large parts of examples in the diffraction process.Understanding the diffraction process is very improtant in the study of small x physics in high-energy nuclear physics,especially for the planned electron-ion collider(EIC)to find gluon saturation.We can use the diffractive dijet production to directly probe the Fourier transfor-m of the gluon Wigner distribution at the EIC.Quantum phase space Wiger distribu-tions of partons have been reckoned as the mother distributions,which contains all the information about parton distributions.People hope to find experimental probes to measure these distributions.The gluon Wigner distributions at a small x can be simplified and written as the Fourier transform of well-known impact parameter dependent dipole amplitudes.We can use the diffractive dijet production to directly probe the Fourier transform of the gluon Wigner distribution.In the MV model,the Fourier transform of the distribution function of small x GTMD can be simplified and computed,and this allows us to plot a 3d image of xW as functions of q? and b?.In order to understand the diffraction process,the thesis focuses on the relation and difference between the classical diffraction,quantum diffraction,high-energy s-cattering diffraction process.In classical optics,the process can be calculated by using Fresnel-Kricahhoff formula when a beam of plane wave scatters the barriers.Fraunhofer diffractionon is what we are interested in,in view of the applicatial of optical concepts to hadronic phenomena.By analyzing the fraunhofer diffraction,we can get the optical theorem.We also can obtain optical theorem from the perspective of quantum mechanics and quantum field theory.The optical theorem constructs the relation between optical diffraction,quantum mechanics and quantum field theory.In addition to optical theorems,classical optics and high energy scattering diffraction have some connections and differences.A plane wave is incident on an aperture and forms a diffraction pattern on the screen behind.And the elastic scattering has sim-ilar image in QCD.When we analyze classical diffraction,we can find that classical diffraction total scattering cross section corresponds to the high-energy total scatter-ing cross section,the classical diffraction scattering cross section corresponds to the high energy elastic scattering cross section,the classical diffraction absorption cross section corresponds to high energy inelastic scattering cross section.Although the classical diffraction has something similar to the high energy scattering diffraction,but there are two essential differences.