Nucleon Structure And Spin Asymmetry In High Energy Pp Process

As people go deep into the nucleon's structure,the spin distribution of the nucleon sea became an attractively important frontier problem,especially when a semi-inclusive DIS precess measured by HERMES shows a contradicive result for the strangeness quarks distribution with all former experimental results gotten from inclusive DIS experiment.This interesting results attract people's attention.It is pointed out in this thesis that thorough investigation about antihyperon's polarization and double spin asymmetry of strangeness particles in high energy pp processes may provide important information about the spin distribution of the nucleon sea.Systematic studies have been carried out for those two spin asymmetry at RHIC energy within the framework of the factorization theorem.Firstly,we presented the general formulae for antihyperon's polarization in singly polarized pp collision under the assumption that the factorization theorem is valid and calculation the dependence of the antihyperon's polarization on different factors.Then we use a well-known Monte-Carlo generator PYTHIA to calculate the fractional contribution of different subprocess to final antihyperon's production.The results demonstrate clearly that the sea quarks which experienced the parton level hard scattering,their fragmentation providing the dominance contribution to the antihyperon's production; meanwhile,the antihyperon's production ratio shows different flavor dependence on the nucleon sea.Then we adopting different spin related fragmentation functions and diverse polarized patton distribution functions as input and systematically delivered the numerical results of different antihyperon's polarization.Sensitivities have been found between the antihyperon's polar- ization and the polarization of the sea quarks' polarization,and the model dependent on the fragmentation process takes less effect.Specifically,(?)⁰ and (?)⁺ antihyperon's polarization is sensitive to the strange quarks' polarization of the initial nucleon;(?)^- and(?)⁺ antihyperon's polarization is sensitive to the light flavor quark's polarization.Precise measurements about the antihyperon polarization in high energy pp process may provide us a new method to study the longitudinal polarized nucleon sea's structure.The double spin asymmetry of pp collision is the production of two polarized patton distribution functions,it should be generally small than the singly longitudinally asymmetry.However,as people do not need to measure the final particles' polarization,we can study the Kaon meson' ALL as well as those hyperon and antihyperon.As Kaon has high production ratio and high experimental statistics and it is not involved with polarized fragmentation function,study its double spin asymmetry will be helpful to understand nucleon sea quark's polarization.In this thesis,a detailed study for antihyperon's double spin asymmetry A_LL in pp collision with doubly longitudinally polarized beams have also been presented as well as for K_S⁰ meson.Numerical analysis shows that similarly to result about the antihyperon's polarization,(?) antihyperon and A antihyperon's double spin asymmetry depend on the strange quarks' distribution of initial proton very much and(?) antihyperon's double spin asymmetry also shows sensitivity to the light flavor sea quark's distribution.A model calculation for the strange particle's transversely single spin asymmetry have also been carried out at this thesis.Numerical results versus the kinematic variables such as Feymann-x scale will provide references for the future experimental investigation.