Energy loss and flow of heavy quarks in gold+gold collisions at center of mass energy = 200 GeV.

摘要

Two of the most interesting results to come from the heavy ion program at the Relativistic Heavy Ion Collider (RHIC) are the observation of jet suppression and elliptic flow. The production of light mesons from Au+Au collisions is suppressed at large momentum compared to that from p+p collisions at the same energy per nucleon when the number of nucleon-nucleon collisions is taken into account. Secondly, the meson production is highly asymmetric with respect to the reaction plane, the plane formed by the impact parameter and the beam axis, indicating strong collective behavior of produced particles, consistent with hydrodynamic expansion.; Jet suppression and azimuthal anisotropy of mesons containing heavy quarks can in principle give more direct information about the properties of the medium than can light mesons. At RHIC, charm and bottom quarks are believed to be formed exclusively in the initial hard nucleon scatterings, predominately by gluon-gluon fusion. Since the heavy quarks are formed early in the collision, their spectrum is sensitive to the entire lifespan of the medium formed. Heavy quarks are predicted to lose less energy than light quarks traversing the medium due to the "dead-cone" effect, and as such could be more sensitive to medium effects than are the light quarks.; This dissertation details the measurement of electrons from heavy quark decays from Au+Au collisions at sNN = 200 GeV using the PHENIX detector over a transverse momentum range of 0.3 GeV/c pT 9.0 GeV/c. The measurement of the azimuthal anisotropy with respect to the reaction plane of electrons from heavy quark decays is also presented. The results of the measurement are compared to predictions from recent theoretical work. It is found that the energy loss models used to describe the light meson suppression are insufficient to describe the suppression of electrons from heavy quarks. Models based on collective motion of the heavy quarks with the medium which give a simultaneous description of the suppression and anisotropy of heavy quarks provide evidence that the bulk properties of the medium can be extracted by the data presented in this thesis.