Azimuthal Anisotropy Of K_S～O And ∧+? Production At Mid-Rapidity From Au+Au Collisions At SNN～(1/2)=130 GeV And Erraticity Behaviour Of Event Factorial Moments In Hadron-Hadron Collisions

The operation and first collisions of Au nuclei in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) during year 2000 began a new era in the study of nuclear matter at high energy density and the search of Quark-Gluon Plasma (QGP). The properties of the QGP and the transition to it have to be identified from the final state which is of a hadronic nature. Measurements of azimuthal anisotropies in the transverse momentum distribution of particles can probe the very early stages of ultra-relativistic heavy-ion collisions. This dissertation presents the STAR results on the azimuthal anisotropy parameter v-i for strange particles K^, A arid A at mid-rapidity in Au+Au collisions at ^/SNN = 130 GeV at RHIC. The value of w2 as a function of transverse momentum pt and collision centrality is presented for both particles up to ~ 3.0 GeV/c. A strong pt dependence in u2 is observed up to 2.0 GeV/c. The w2 measurement is compared with hydrodynamic model calculations. The physics implication of the pt integrated v% magnitude as a function of particle mass is also discussed.Erraticity analysis provide new opportunity in measuring event by event fluctuations in high energy nuclear collisions. In the second part of this dissertation (chapter 6 and chapter 7), it is demonstrated that in low multiplicity sample, the increase of the fluctuation of event factorial moments with the diminishing of phase space scale, "erraticity", are dominated by the statistical fluctuations. Applying erraticity analysis to high multiplicity sample at RHIC and LHC energy is recommended.