The Dileptons, Photons And Light Vector Mesons Production In Ultrarelativistic Nucleus-nucleus Collisions

In the ultrarelativistic heavy ion collisions, the perturbative Quantum Chromody-namics (pQCD) predicts that the energy density in the center of the collision can be high enough to form the quark matter. In high energy heavy-ion collisions, the energy density in the center of the collision can be high enough that can make matter leave the hadronic phase into the quark matter (Glasma and quark-gluon plasma), then the quark matter will expanding and cooling back to the hadronic phase. When matter is in the Glasma and the quark-gluon plasma phase, the dileptons, photons and light vector mesons produced by the partons interaction will carry the information of quark matter.In this thesis, we investigate the the formation of quark matter produced in the relativistic nucleus-nucleus collisions, its space-time evolution, and the production of dileptons, photons, and light vector mesons from the hard photoproduction process, color glass condensate (CGC), Glasma, quark-gluon plasma (QGP), and hadronic gas (HG) at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies.At the early stage of the relativistic nucleus-nucleus collisions, the large trans-verse momentum dileptons, photons, and light vector mesons are mainly from the hard scattering processes of the initial partons, the hard photoproduction processes, and the fragmentation processes. The mainly hard scattering processes of the partons are quark-antiquark annihilation, quark-gluon Compton scattering, and gluon-gluon fusion pro-cesses. The hard photoproduction processes contains elastic double-photon process, semielastic (direct and resolved) photoproduction processes, and inelastic (direct and resolved) photoproduction processes. In the direct photoproduction processes, the high-energy photon emitted from the nucleus or the charged parton of the incident nucleus interacts with the parton of another incident nucleus by the interaction of quark-photon Compton scattering and gluon-photon fusion processes to form the dileptons, photons, and light vector mesons. In the resolved photoproduction processes, the uncertainty principle allows the high-energy hadron-like photon for a short time to fluctuate into a quark-antiquark pair which then interacts with the partons of another incident nucleus by quark-antiquark annihilation, quark-gluon Compton scattering, and gluon-gluon fu-sion processes to form the dileptons, photons, and light vector mesons. Indeed, for the fragmentation processes, the quark (or gluon) jets can pass through the quark-gluon plasma and lose their energy before fragmenting into dileptons, photons, and light vec-tor mesons. The numerical results indicate that the contribution of photoproduction processes and fragmentation processes for the dileptons, photons, and light vector me-son production becomes evident at Large Hadron Collider (LHC) energies.Furthermore, based on the idea of gluon saturation in the color glass condensate (CGC) framework, the gluon density with transverse momentum less than the saturation momentum Qs will reach a high value, then the two colliding nuclei with high gluon density can form the high gluon density Glasma state. In the ultrarelativistic case, the value of saturation momentum Qs becomes larger than the Quantum Chromodynam-ics (QCD) confinement scale AQCD, which implies that as(Qs)<<1. Hence we can derive the production rate for the dileptons, photons, and light vector mesons in the KT-factorization approach. In the color glass condensate gluon saturation approach, the mainly production processes for the dileptons, photons, and light vector mesons are gluon-gluon fusion processes. The numerical results indicate that the dileptons, pho-tons, and light vector mesons from the color glass condensate becomes prominent in p-p, Au-Au, p-Pb and Pb-Pb collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies.Indeed, based on the idea of gluon saturation in the color glass condensate (CGC) framework, the energy density for the center of the relativistic nucleus-nucleus colli-sions is high enough to form the high gluon density Glasma state, that have not reached the thermal equilibrium. In gluons saturation region, the value of saturation momen-tum Qs becomes larger than the Quantum Chromodynamics (QCD) confinement scale ΛQCD, which implies that as(Qs)<<1, then the Glasma can be treated as a weak cou-pling system, and expands hydrodynamically with near perfect fluid. In the Glasma, the low mass dileptons are mainly from the quark-antiquark annihilation processes, and the low transverse momentum photons are mainly from quark-antiquark annihila-tion, quark-photon Compton scattering and gluon-photon fusion processes, and as is the gluon Glasma dominated, so that the most important contribution of the low transverse momentum photons photons is from the gluon-gluon fusion processes. The numerical results indicate that the low mass dileptons and low transverse momentum photons from the Glasma become important at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies.In addition, with the expansion of the Glasma, the Glasma will thermalize into the quark-gluon plasma (QGP) at the proper time τth.In the quark-gluon plasma, the thermal dileptons are mainly from quark-antiquark annihilation, and the thermal pho-tons are mainly from quark-antiquark annihilation and quark-gluon Compton scattering processes. Furthermore, the quark (or gluon) jets from the early stage of the relativis-tic nucleus-nucleus collisions can pass through the quark-gluon plasma and lose their energy before interacting with the thermal partons of the hot-dense medium to form the thermal dileptons, thermal photons, and light vector mesons. The numerical results indicate that the contribution of jet-medium interaction for dileptons, photons, and light vector mesons producction becomes evident at Large Hadron Collider (LHC) energies.Finally, as the expansion of the quark-gluon plasma cooling to the critical temper-ature, the thermal system will reach the quark-gluon plasma and hadronic mixed phase, and completely drop into the hadronic phase at the proper time τH, then the hot hadronic gas expansion and hadronic freeze-out temperature Tf achieved at the proper time τf. In the hot hadronic gas, the low mass dileptons are mainly from ππ�'l+l- processes, and the low transverse momentum photons are mainly from ππ�'γγ,ππ�'γρ,ππ�'γη, πρ�'γπ, and πη�'γπ processes. Since αρ=2.9, the most important production process for thermal photons is πρ�'γπ process. The numerical results indicate that the thermal dileptons and thermal photons from the hadronic gas become prominent at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies.