Dilepton Production Of Drell-Yan Pross In PA Collision And Nuclear Effect To The Pt Spectrum

According to the two basic features of QCD:Asymptotic freedom and quark confinement, the former refers to the greater is the exchange of transverse momentum between quarks, or, equivalently, the less is the separation between them, the less is their interaction; the last refers to quarks are generally confined into hadron, and the free quark cannot be observed experimentally.QGP, a new state of matter, may be created in the extreme circumstances of high temperature and density which's formed by relative heavy iron collision(RHIC). In the transient moment of coexistence between quarks and gluons, some important signals that confirm the realness of QGP would emerge due to interactions of components of QGP, therefore, studying those signals become presently a hot topic in high energy physics.One of the most important signals developed by dilepton is considered in this thesis, according to QCD, a quark-antiquark pair in QGP can be annihilated into a virtual photon, and then decay into dilepton. The production rate:the distribution of transverse momentum and rapidity of dilepton depend on the mass distribution of quarks and gluons in QGP within the domain of collision, we can obtain some knowledge of the existence and thermal conditions of QGP via the information from dilepton.Besides the way of the creation of dilepton mentioned above, there're another background processes can produce dilepton. It's necessary studying those background processes to obtain the contribution of them. In this thesis, Drell-Yan process is considered, which is one of great contribution of dilepton. The motivation of this consideration is to explore the influence on dilepton production and its distribution of transverse momentum by virtue of nuclear effect. Since that after the leptons go through QGP, there is almost no interaction between lepton and QGP, when we analyse the influence, we can ignore the unclear effect of final state and take notice of the unclear screen effect of initial state. By this viewpoint, the thesis starts on Per-turbative Quantum Chromodynamics, on this basis, we calculate the scattering cross section and transverse momentum spectrum of hard processes of dilepton production from Drell-Yan processes in unclear-unclear collision, by introducing the distribu-tion function of nuclear parton, we calculate numerically the transverse momentum spectrum. In chapter 4, we take nuclear effect of initial state into account, calculate numerically the transverse momentum spectrum of dilepton in Drell-Yan process of pA collision. finally, we compare this result with pp collision, analyse the influence on transverse momentum spectrum of dilepton by virtue of nuclear effect of initial state.