Particles Produced in Association with High Transverse Momentum Single Photons and $\pi^0$s in Hadronic Collision

Abstract

The charged and neutral particles produced in association with high transverse momentum ($Pr_{\tau}$ > 5.0 GeV /c) photons ($\gamma$) and neutral pions ($\pi^0$) in p(Cu+Be) and $\pi^-$(cu+Be) collisions at vs = 31.5 GeV are studied in this thesis. It was observed that 1) The relative rapidity of the two highest Pr recoiling particles in the events have a jet - like structure. 2) The relative rapidity of the single $\gamma$ (or $\pi^0$ ) and the highest $P_{\tau}$ charged particle accompanying the single $\gamma$ (or $\pi^0$ ) show that the high $P_{\tau} \pi^0$ events have a jet - like structure in the trigger hemisphere whereas the high $P_{\tau}$ single $\gamma$ events do not. 3) The angular distributions of the particles produced in the reactions show that high $P_{\tau} \pi^0$s are accompanied by other particles, whereas high $P_{\tau}$ single photons are relatively isolated. 4) The fragmentation distributions of the recoiling particles from the high $P_{\tau}$ single photons and $\pi^0$s are consistent with the measurements of other experiments. 5) The recoiling particles are consistent with the fragmentation of either a quark or a gluon according to the QCD (Quantum Chromodynamics). In summary, particles produced in association with high transverse momentum single photons and $\pi^0$s in hadronic collisions have been measured and their properties are in good agreement with the predictions of the parton model and those of QCD