High pT direct photon and π0 triggered azimuthal jet correlations and measurement of kT for isolated direct photons in p+p collisions at √s=200GeV

Abstract

Correlations of charged hadrons of 1 <15Gev/c are used to study jet fragmentation in the γ+jet and dijet channels, respectively. The magnitude of the partonic transverse momentum, kT, is obtained by comparing to a model incorporating a Gaussian kT smearing. The sensitivity of the associated charged hadron spectra to the underlying fragmentation function is tested and the data are compared to calculations using recent global fit results. The shape of the direct photon-associated hadron spectrum as well as its charge asymmetry are found to be consistent with a sample dominated by quark-gluon Compton scattering. No significant evidence of fragmentation photon correlated production is observed within experimental uncertainties. © 2010 The American Physical Society.