Study On Pion Parton Distribution Function

High energy physics experiments implied nucleon is constructed by point-like particles (quarks). Richard Feynman and others introduced parton to describe interior nature of nucleons in high energy scattering experiments. A lot of theoretically and experimental researches are focused on the parton distribution functions. We know the structure more clearly through the scattering experiments. Thus after pion was theoretically presented by Yukawa Hideki and discovered in 1947, a few researches are focused on the pion parton distribution. Although those researches are not as thoroughly as researches focusing on nucleon, there are still many useful results and information. Researchers found some reliable pion valence quark distributions. Some useful models of pion parton distributions are GRV-π, SMRS and GRS model.The DGALP evolution equation describes dynamic evolution of partons in Quantum Chromodynamics. Because of the radiation of the partons, the destiny of gluon in small x range will be larger and larger, and the unitarity of the cross section will be destroyed through the evolving of partons. The ZRS evolution equation considers both the shadowing and anti-shadowing effects in evolving process, and therefore we use ZRS evolution equation to reseach pion parton distribution functions.We research about pions mainly in these points:1. We simply analyze the work of GRV-π, GRS and SMRS, and try to understand the similarity and difference between their valence quark distributions. We also present the valence, sea quark and gluon distributions of related references.2. We introduce the ZRS evolution equation, and provide methods about how to use this equation in pion.3. Through using the ZRS evolution equation and E615 pion-nucleon scattering experiment data, we found a new set of pion parton distributions. The new fit result is found when the initial input has only valence quark input and Q02=0.074GeV2, then it was evolved with the ZRS evolution equation. Our result can explain the experiment data well.4. We analyze the momentum distributions of protons in our result, and use the SMRS momentum distributions to contrast our result. We also try to provide a few advices for improvements of our research.In general, we build a new result about pion parton distributions, and it is different with other models because our initial input only has valence quark distributions. With evolving by ZRS evolution equation, we can explain pion valence quark distribution and structure function experimental data well, and the distributions of nucleon momentum carried by pion partons are similar to other models.