Transverse Momentum Correlations In π～+p And K～+p Collisions At √s=22GeV And Transverse Momentum Correlations And Azimuthal Correlations In Relativistic Heavy Ion Collisions

Quantum Chromo-Dynamics (QCD). predicts that nuclear matter undergoes a phase transition to a deconfined state of quark and gluon at extreme densities and temperatures. The condition of the extreme high energy density and temperature could be created in high energy heavy-ion collision experiments, then to study the new-matter state quark-gluon plasma (QGP), which is one of the goals that high energy and nuclear physics scientists all over the world have been searching for collaborative since several past decades.Event-by-event transverse momentum fluctuations have been considered as a good variable to distinguish the QGP phase from hadronic matter phase and describe the degrees of system thermalization.With the increasing of collision energy, the number of the final state particles in a single event become large enough for people to investigate the single event or event-by-event fluctuations of a certain variable.In this article, different event-by-event transverse momentum fluctuation measures are summarized. According the common and essential part, we define normalized two-particle transverse momentum correlations.Meanwhile, the search for any exotic behavior of quark-gluon plasma in nucleus-nucleus collisions also requires a comparison with what is expected from phenomeno-logical nucleon-nucleon extrapolations. It is therefore necessary to determine what is expected from such extrapolations based on information from nucleon-nucleon data. However, exactly how the transverse expansion relates to the longitudinal one is unexplored even for the elementary collision. So the rapidity, azimuthal and multiplicity dependence of mean transverse momentum and transverse momentum correlations arc studied inÏ€⁺p and k⁺p collision at (?)s =22GeV, and the data come from NA22 collaboration. For the first time, it is found that the rapidity dependence of two-particle transverse momentum correlations is different from that of the mean transverse momentum, and they have a similar multiplicity dependence. In particular, the transverse momentum correlation is boost-invariant. A strong azimuthal dependence of the transverse momentum correlations comes from the constraint of energy-momentum conservation. The results are compared with those from the PYTHIA Monte Carlo generator. The similarities to and differences with the results from current heavy ion experiments are discussed.The expansion of the system may be impelled by re-scattering of final state par- tides. The centrality dependence of mean transverse momentum and transverse momentum correlation has also been studied using RQMD Monte Carlo generator. There is a visible increase of mean transverse momentum with increasing impact centrality. but transverse momentum correlation has opposite monotonic dependence. The re-scattering of final state particles can enhance the velocity of transverse expansion, however, there is hardly influence on the two-particle transverse momentum correlation.Relativistic heavy ion collisions provide a good condition, in which we can study the character of the matter at extreme densities and temperatures. Anisotropic azimuthal flow in the transverse momentum plane of final state particles, as an important kind of collective flow, has been considered as a good tools to searching the new matter formed in the collision, and we can get the information the early partonic collectivity behave in high energy nuclear collisions. Elliptic flow measures the correlation of the azimuth angle of an emitted particle and the azimuth of the reaction plane, is one kind of anisotropic flow. It is thought to be driven by pressure built up early in the collision and, therefore, can reflect conditions existing in the early collision. Compared with the measure of elliptic flow, the measure of the two-particle correlation C^ab(δφ) and the azimuthal charge balance function B(δφ) have several advantage, and provide some information of non-flow. In this article, we also study elliptic the dependence of flow v₂ on multiplicity and event mean transverse momentum. The behaviors of three azimuthal correlation measurements, anisotropic flow, azimuthal balance function, and two-particle azimuthal correlation in RQMD model and AMPT model are demonstrated and compared. It is found that two-particle azimuthal correlation has the same centrality dependence as that of anisotropic flow. The contributions of momentum conservation in two-particle azimuthal correlation are concentrated in large angle correlations and are well separated from the small angle correlations caused by anisotropic transverse momentum distribution. While, the centrality dependence of the azimuthal charge balance function is different from those of anisotropic flow and two-particle azimuthal correlation, which indicates that the charge balance function is not a direct presentation of anisotropic flow, already predicted from thermal models.