Drell-Yan Production With Parton Energy Loss In Cold Nuclei

It is expected that quark-gluon plasma (QGP) will be produced in an extreme high temperature and density condition in relativistic heavy ion collisions. Because the initial-state objects of collisions are nucleus instead of nucleons, nucleus-nucleus collisions are not the simple superposition of nucleon-nucleon collisions even without the influence of QGP in the final-state. Drell-Yan process is an ideal tool to study the initial state cold nuclear matter (CNM) effects. The parton energy loss effect, an important aspect of cold nuclear matter effects, will suppress the production rate of dilepon with large transverse momentum. The final-state dilepton interact with the charged particles in nuclear matter only though electromagnetic interaction. It’s mean free path of is much larger than the nuclear matter size, therfore dileptons can be hardly influenced by final state effects. Drell-Yan process provides a relatively clean signature for initial-state effects. In the thesis we study the influence of nuclear shadowing effect, especially initial-state parton energy loss effect to Drell-Yan process.In the framework of perturbative QCD, we calculate the triple differential cross section d3a/dMdydpr for Drell-Yan process at leading-order(LO). Using the CTEQ6L parametrization set of parton distribution functions (PDFs), we provide the trans-verse momentum distribution of dilepton in p+p collisions. For the nuclear shadow-ing effect, the nuclear parton distribution functions (nPDFs) are modified by EPS09. Through comparing with the results in p+p collision, the results in p+A collision reveal that both dilepton transverse momentum spectra and invariant mass spectra are suppressed. The dilepton rapidity distribution shows an obvious suppression in forward rapidity region. Later we briefly introduce the opacity expanding method in GLV model, with which we obtain the numerical results of initial-state parton energy loss in heavy-ion collisions. The nuclear modifications for dilepton transverse momentum spectra, dilepton invariant mass spectra and dilepton rapidity spectra due to CNM effects are calculated by employing three different parametrization. sets of nPDFs (EPS09, nDS and HKN) in p+A and A+A collisions. The results show that the total suppression becomes more obvious owing to the initial-state parton energy loss effect. The suppression due to initial-state parton energy loss always in-creases with the transverse momentum, but it is insensitive to the dilepton invariant mass and rapidity. The nuclear modification factor R shows a symmetric rapidity distribution in A+A collisions under RHIC and LHC energy region. The deviation among different parametrization sets of nPDFs is appreciable for dilepton transverse momentum spectra.