Abstract
We report on the event structure and double helicity asymmetry () of jet production in longitudinally polarized collisions at . Photons and charged particles were measured by the PHENIX experiment at midrapidity with the requirement of a high-momentum () photon in the event. Event structure, such as multiplicity, density and thrust in the PHENIX acceptance, were measured and compared with the results from the pythia event generator and the geant detector simulation. The shape of jets and the underlying event were well reproduced at this collision energy. For the measurement of jet , photons and charged particles were clustered with a seed-cone algorithm to obtain the cluster sum (). The effect of detector response and the underlying events on was evaluated with the simulation. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order and perturbative quantum chromodynamics jet production cross section. For with an average beam polarization of we measured at the lowest bin () and at the highest bin () with a beam polarization scale error of 9.4% and a scale error of 10%. Jets in the measured range arise primarily from hard-scattered gluons with momentum fraction according to pythia. The measured is compared with predictions that assume various distributions based on the Gluck-Reya-Stratmann-Vogelsang parameterization. The present result imposes the limit at 95% confidence level or at 99% confidence level.
15 More- Received 27 September 2010
DOI:https://doi.org/10.1103/PhysRevD.84.012006
© 2011 American Physical Society