Phenomenological Study On The Strange Radius And Charge Distribution Of Nucleon

The internal structure of nucleons has always been an important research topic in hadron physics.From the beginning of the last century,this with the constant improvement of the experiment tools for decades,the advance of theory and method,using the theory of Quantum Chromodynamics(QCD)in perturbation on the high energy region to solve the problems,to the internal structure of nuclear also has a certain degree of understanding,but in the low energy region,perturbation QCD failure,at present,we still need some phenomenological model is set up.The Jefferson Laboratory in the United States announced that they used the world's most accurate electroweak coherence experiment to measure:proton strange magnetic moment is positive,strange electric shape factor is negative.The latter means that the strange radius of the proton is positive.In general,the anti-strange quark s in the proton moves closer to the center of mass of the proton than the strange quark s.This contradicts the predictions of most theories.In the classical theory in the image:proton consists of two parts,part consists of three quarks(uud)and a certain distance between,and the other part is strange quarks and the composition of the strange quarks strange quarks(ss)and take the form of gluons perturbation fluctuation,this means that the strange quarks for proton magnetic moment and strange radius.Nonperturbed pairs of strange quarks may exist in protons.Existing theoretical analysis shows that the penta-quark component in the proton may exist in the form of penta-quark pairs of colored groups.In 2007,G.A.Miller found that the central charge densities of neutron was negative,contrary to theoretical predictions.For example,from the meson cloud model,the charge densities of the neutron center may be positive.But in fact the central charge densities of neutron is negative which supports the conclusion that nucleon contain penta-quark components that have been proposed in recent years.In the new picture,the neutron should have a largeudduu component,the quaternary quark subsystem uddu in the orbital excited state,u in the ground state,with the flavor of[4]_F _S[2 2]_F[2 2]_Ssymmetry the spin configuration is probably the lowest energy configuration,and the antiquarku in the ground state naturally gives the negative charge densities at the center.In this thesis,we will give a brief review of the discovery process of elementary particles and the four fundamental interaction forces,and give a brief introduction to the classical standard model of tri-quark in elementary particle physics.Then the specific content of the study includes:in the baryon structure in addition to considering the three quark components,but also consider the five quark components,using group theory and relevant knowledge to construct the three quark system and the five quark system color,taste,spin and space wave function.On the basis of the wave function,the strange radius of the penta-quark configuration including the lowest energy,the charge distribution of the proton and the neutron,are calculated,analyzed and discussed.Based on the consideration of the diagonal matrix element only,the calculation results of the strange radius show that the strange radius of the spatial wave function with[3 1]_X symmetry is positive,and the result of the spatial wave function with[4]_X symmetry is negative.The theory predicts that the singularity radius of the proton is negative.Compared with the theory,the experimental results show that there areuudss penta-quark components in the proton,and the parity is positive.The main composition of baryon is no longer just the form of three-quark composition,but on the basis of the three-quark composition plus the penta-quark composition in the form of color quark group,the mechanism of mixing the penta-quark composition and the tri-quark composition is feasible.Analysis and discussion,in this thesis the strange radius of the proton and the analysis of the charge density of the protons and neutrons and discussion shows that there is a real five quarks in nuclear components,the calculation results made us the research on nuclear structure had the further understanding,which lay the solid foundation for the other properties of the analysis of nuclear,provide certain theoretical support for hadron physics experiment.